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Scientific Data Documentation
Linked Birth/Infant Death File, 1995
Linked Natality 1995 Data Set Names (DSNs)
	CC36.NATAL95.LINK
	CC36.NATAL95.DENOM
	CC36.NATAL95.UNLINK
	CC36.NATAL95.LINK.PRVIG
	CC36.NATAL95.DENOM.PRVIG
	CC36.NATAL95.UNLINK.PRVIG


LINKED BIRTH/INFANT DEATH DATA SET 1995 PERIOD DATA


SPECIAL NOTICE:

THE GEOGRAPHIC CODES WERE CHANGED EFFECTIVE WITH 1994 DATA TO REFLECT 
THE RESULTS OF THE 1990 CENSUS

BIRTHS AND DEATHS FOR PUERTO RICO,VIRGIN ISLANDS AND GUAM ARE INCLUDED 
IN SEPARATE DATA FILES        


This tape documentation was prepared in the Division of Vital Statistics.  Linda Biggar, Systems,
Programming and Statistical Resources Branch and Marian MacDorman, Reproductive Statistics
Branch, wrote the tape documentation.  Marian MacDorman coordinated preparation of the 1993
Mortality Technical Appendix; Sherry Murphy, Mortality Statistics Branch, wrote the 1995
Mortality Addendum.  Sally Clarke of the Reproductive Statistics Branch coordinated
preparation of the 1994 Natality Technical Appendix and 1995 Addendum.  The Registration
Methods Branch and the Technical Services Branch provided consultation to State vital statistics
offices regarding collection of birth and death certificate data.  
Questions about the data tape and documentation should be directed to the Systems,
Programming and Statistical Resources Branch, Division of Vital Statistics, NCHS, 6525
Belcrest Road, Room 840, Hyattsville, MD 20782 Ph: (301) 436-8900.
General questions about linked file data should be directed to Marian MacDorman, Reproductive
Statistics Branch, Division of Vital Statistics, NCHS, 6525 Belcrest Road, Room 840,
Hyattsville, MD 20782 Ph:  (301) 436-8954 x171.



Linked Birth/Infant Death Data Set   1995 Period Data
Contents
1.   Introduction, Methodology, and Classification of Data.
2.   Machine used, file and data characteristics.
3.   List of data elements and locations.
4.   Record layout and definition of items and codes.
5.   County geographic codes available on the public-use file.
6.   City geographic codes available on the public-use file.
7.   Titles and codes for the 61 cause-of-death list.
8.   Documentation tables 1-6.
9.   1995 Addendum to the 1994 Natality Technical Appendix.
10.  Technical Appendix for the 1994 Natality file.
11.  1995 Addendum to the 1993 Mortality Technical Appendix.
12.  Technical Appendix for the 1993 Mortality file. 



SYMBOLS USED IN TABLES
Symbol         Explanation
---            Data not available
...            Category not applicable
  -            Quantity zero
0.0            Quantity more than 0 but less than 0.05
  *            Figure does not meet standards of reliability or precision


Introduction
This data set represents the first release of linked birth/infant death data in a new format. 
Beginning with 1995 data, the linked file will be released in two different formats   period data
and birth cohort data.
Period data   The numerator for the period linked file for 1995 consists of all infant deaths
occurring in 1995 linked to their corresponding birth certificates, whether the birth occurred in
1995 or 1994.  The denominator file for this data set is the 1995 natality file, that is, all births
occurring in 1995.
Birth cohort data   The numerator of the birth cohort linked file for 1995 consists of deaths to
infants born in 1995 whether the death occurred in 1995 or 1996. The denominator file is the
1995 natality file, that is, all births occurring in 1995.  This file will be available about one year
after the release of the period linked file.   
The release of linked file data in two different formats allows NCHS to meet customer demands
for more timely linked file data while still meeting the needs of data users who prefer the birth
cohort format.  While the birth cohort format has methodological advantages, it creates
substantial delays in data availability, since it is necessary to wait until the close of the following
data year to include all infant deaths to the birth cohort. 
This documentation is for the 1995 period linked file. Beginning with 1995 data, the period
linked file will form the basis for all official NCHS linked file statistics (except for special cohort
studies). 
The 1995 period linked birth/infant death data set includes three separate data files.  The first 
file includes all infant deaths which occurred in the 1995 data year linked to their corresponding 
birth certificates, whether the birth occurred in 1995 or in 1994 - referred to as the numerator file. 
The second file contains information from the death certificate for all infant death records which
could not be linked to their corresponding birth certificates - referred to as the unlinked death
file.  The third file is the 1995 NCHS natality file in compressed format, which is used to provide
denominators for rate computations. The denominator file is included on the CD-ROM version
of this data set.  For the data tape version, the data user has the option of purchasing linked file
data either with or without the denominator file, to reduce costs for data users who had
previously purchased the NCHS natality file.
Changes Beginning with the 1995 Data Year         
In part to correct for known biases in the data, changes have been made to the linked file
beginning with the 1995 data year.  A weight has been added to the linked numerator file to
correct in part for biases in percent linked by major characteristics (see section on Percent of
records linked below). The number of infant deaths in the linked file are weighted to equal the
sum of the linked plus unlinked infant deaths by age at death and state.  The formula for
computing the weights is as follows: 
     number of linked infant deaths + number of unlinked infant deaths
               number of linked infant deaths.                            
A separate weight is computed for each State of residence of birth and each age at death 
category (<1 day, 1-27 days, 28 days-1year). Thus, weights are 1.0 for states which link all 
of their infant deaths.  The denominator file is not weighted.  Weights have not been computed for 
the Puerto Rico, Virgin Islands, and Guam file. 
An imputation for not-stated birthweight has been added to the data set, to reduce potential 
bias in the computation of birthweight-specific infant mortality rates.  Basically, if birthweight 
is not-stated and the period of gestation is known, birthweight is assigned the value from the 
previous record with the same period of gestation, race, sex, and plurality.  Imputed values are 
flagged. The addition of this imputation has reduced the percent of not-stated responses for 
birthweight from 3.15% to 1.19% in the numerator file, and from 0.10% to 0.04% in the denominator 
file, thus reducing (but not eliminating) the potential for underestimation when computing
birthweight-specific infant mortality rates.   
Other changes include the addition of the clinical estimate of gestation, as reported on the 
birth certificate.  This variable was added to provide additional information on gestational age.  
For the first time, data for Puerto Rico, the Virgin Islands, and Guam were included in separate 
data files in the 1995 linked data set.  The change from a birth cohort to a period format was 
discussed in detail on page one. 
Comparisons of infant mortality data from the linked file with infant mortality data from the
unlinked mortality file
Although the time periods are the same, numbers of infant deaths and infant mortality rates 
are not identical between the 1995 period linked file and the 1995 unlinked mortality file.  The
differences can be traced to three different causes: 1) geographic differences; 2) additional
quality control; and 3) weighting. 
Geographic differences   To be included in the linked file for the 50 States and D.C., the birth
and death must both occur inside the 50 States and D.C.  In contrast, for the unlinked mortality
file, deaths which occur in the 50 States and D.C. to infants born inside and outside of the 50
States and D.C. are included.  Similarly, to be included in the linked data file for Puerto Rico, the
Virgin Islands, and Guam, the birth and death must both occur in Puerto Rico, the Virgin Islands
or Guam.  In contrast, for the unlinked mortality file, deaths which occurred in Puerto Rico, the
Virgin Islands, and Guam to infants born inside and outside of Puerto Rico, the Virgin Islands
and Guam are included.  
Additional quality control   The second reason for differences in numbers of infant deaths
between the linked and unlinked data sets is that the linkage process subjects infant death records
to an additional round of quality control review.  Every year, a few records are voided from the
file at this stage because they are found to be fetal deaths, deaths at ages greater than 1 year, or
duplicate death certificates.  
Weighting   The third reason for differences between the linked and unlinked data relates to
new weighting procedures added to the linked file in 1995.  Beginning with 1995 data, linked file
records were weighted to compensate for the 2-3 percent of infant death records which could not
be linked to their corresponding birth certificates.  Although every effort has been made to design
weights which will accurately reflect the distribution of deaths by characteristics, weighting may
contribute to small differences in numbers and rates by specific variables between the linked and
unlinked mortality files. 
In most cases, differences between numbers of infant deaths and infant mortality rates between
the linked file and those computed from the unlinked mortality file are negligible.  
                                 
Methodology
The methodology used to create the national file of linked birth and infant death records takes
advantage of two existing data sources:  
1.   State linked files for the identification of linked birth and infant death certificates; and 
2.   NCHS natality and mortality computerized statistical files, the source of computer
     records for the two linked certificates.  
Virtually all States routinely link infant death certificates to their corresponding birth certificates
for legal and statistical purposes.  When the birth and death of an infant occur in different States,
copies of the records are exchanged by the State of death and State of birth in order to effect a
link.  In addition, if a third State is identified as the State of residence at the time of birth or
death, that State is also sent a copy of the appropriate certificate by the State where the birth or
death occurred.
The NCHS natality and mortality files, produced annually, include statistical data from birth and
death certificates that are provided to NCHS by States under the Vital Statistics Cooperative
Program (VSCP).  The data have been coded according to uniform coding specifications, have
passed rigid quality control standards, have been edited and reviewed, and are the basis for 
official U.S. birth and death statistics. 
To initiate processing, NCHS obtained matching birth certificate numbers from States for all
infant deaths that occurred in their jurisdiction.  We used this information to extract final, edited
mortality and natality data from the NCHS natality and mortality statistical files.  Individual birth
and death records were selected from their respective files and linked into a single statistical
record, thereby establishing a national linked record file.  
After the initial linkage, NCHS returned to the States where the death occurred computer lists of
unlinked infant death certificates for follow up linking.  If the birth occurred in a State different
from the State of death, the State of birth identified on the death certificate was contacted to
obtain the linking birth certificate.  State additions and corrections were incorporated, and a final,
national linked file was produced.  Characteristics of the natality and mortality data from which
the linked file is constructed are described in detail in the Technical Appendices and Addenda
included in this document.
Characteristics of Unlinked File
For the 1995 linked file 750, or 2.5% of all infant death records could not be linked to their
corresponding birth certificates. Unlinked records are included in a separate data file in this data
set.  The unlinked record file uses the same record layout as the numerator file of linked birth and
infant death records.  However, except as noted below, tape locations 1-210, reserved for
information from the matching birth certificate, are blank since no matching birth certificate
could be found for these records.  The sex field (tape location 79) contains the sex of infant as
reported on the death certificate, rather than the sex of infant from the birth certificate, which is
not available.  The race field (tape location 36-37) contains the race of the decedent as reported
on the death certificate rather than the race of mother as reported on the birth certificate as is 
the case with the linked record file.  The race of mother on the birth certificate is generally
considered to be more accurate than the race information from the death certificate (see section
on Comparison of race data from birth and death certificates in the 1993 Mortality Technical
Appendix included in this documentation).  Also, date of birth as reported on the death certificate
is used to generate age at death.  This information is used in place of date of birth from the birth
certificate, which is not available. 
Documentation table 6 shows counts of unlinked records by race and age at death for each State
of residence.  The user is cautioned in using table 6 that the race and residence items are based on
information reported on the death certificate; whereas, tables 1-5 present data from the linked file
in which the race and residence items are based on information reported on the birth certificate. 
(see section on Comparison of race data from birth and death certificates in the 1993 Mortality
Technical Appendix included in this documentation). 
Percent of Records Linked
The 1995 linked file includes 28,767 linked infant death records and 750 unlinked infant death
records.  The linked file is weighted to the sum of linked plus unlinked records, thus the total
number of weighted infant deaths by place of occurrence is 29,517.  While the overall percent
linked for infant deaths in the 1995 file is 97.5%, there are differences in percent linked by
certain variables.  These differences have important implications for how the data is analyzed.
Table 1 shows the percent of infant deaths linked by State of occurrence.  While most States link
a high percentage of infant deaths, linkage rates for some States are well below the national
average.  Note in particular the percent linked for California (94.1%), Ohio (89.3%) and
Oklahoma (84.3%).  When a high percentage of deaths remain unlinked, infant mortality rates
computed for these States are underestimated.  It is for this reason that weights were added to the
1995 file to correct for biases in the data due to poor data linkage for particular states.  
The percent of infant deaths linked by race and age at death is shown in Table 2.  In general, a
higher percentage of postneonatal (97.9%) than neonatal (97.2%) deaths were linked.  Percents
linked were similar for white (97.4%) and black (97.5%) infants.  Variations in percent linked by
underlying cause of death have also been noted, particularly a slightly lower percent linked for
ICD-9 No. 765 - Disorders relating to short gestation and unspecified low birthweight (data not
shown).  While the weighting protocol has been designed to correct for possible bias due to
variations in match rates by characteristics, no statistical method can correct perfectly for data
limitations.  Therefore, variations in the percent of records linked should be taken into
consideration when comparing infant mortality rates by detailed characteristics.  
Geographic classification
Geographic codes in this data set have been updated to reflect the results of the 1990 census, 
and differ slightly from those used in previous linked files.  Because of confidentiality concerns, 
only those counties and cities with a population size of 250,000 or more are separately identified 
in this data set.   Users should refer to the geographic code outline in this document for the list 
of available areas and codes.
For events to be included in the linked file, both the birth and death must occur inside the 50
States and D.C. in the case of the 50 States and D.C. file; or in Puerto Rico, the Virgin Islands or
Guam in the case of the Puerto Rico, Virgin Islands and Guam file.  In tabulations of linked data
and denominator data events occurring in each of the respective areas to nonresidents are
included in tabulations that are by place of occurrence, and excluded from tabulations by place of
residence. These exclusions are based on the usual place of residence of the mother.  This item is 


Table 1. Percent of infant deaths linked by state of occurrence of death:  United States, 1995
United States             97.5%         Nebraska             98.5%
     Alabama             100.0%         Nevada              100.0% 
     Alaska              100.0%         New Hampshire        98.4%
     Arizona              97.8%         New Jersey           95.4%
     Arkansas             99.0%         New Mexico           95.7%
     California           94.1%         Upstate New York     98.3%
     Colorado             99.7%         New York City        99.3%
     Connecticut          99.7%         North Carolina       96.9%
     Delaware            100.0%         North Dakota        100.0%
     District of Columbia 99.1%         Ohio                 89.3%
     Florida              99.7%         Oklahoma             84.3%
     Georgia             100.0%         Oregon               99.3%
     Hawaii               98.2%         Pennsylvania         97.8%  
     Idaho               100.0%         Rhode Island         98.0%
     Illinois             98.0%         South Carolina      100.0%
     Indiana              98.1%         South Dakota         99.0% 
     Iowa                 97.4%         Tennessee            99.9%
     Kansas              100.0%         Texas                98.7%
     Kentucky             99.7%         Utah                 99.6%
     Louisiana            97.4%         Vermont             100.0%
     Maine               100.0%         Virginia             97.2%
     Maryland             99.2%         Washington           98.0%
     Massachusetts        96.7%         West Virginia        98.8%
     Michigan             98.0%         Wisconsin           100.0% 
     Minnesota           100.0%         
     Mississippi          99.7%         Puerto Rico               98.8%
     Missouri             98.9%         Virgin Islands           100.0%
     Montana             100.0%         Guam                      97.4%
Table 2. Percent of infant deaths linked by race and age at death: United States, 
1991 birth cohort
(Infant deaths are under 1 year.  Neonatal deaths are under 28 days, and postneonatal, 
28 days through 11 months)
                         All races         White          Black
       Infant                97.5%         97.4%          97.9%
       Neonatal              97.2%         97.3%          97.7%
      Postneonatal           97.9%         98.7%          98.4%

contained in both the denominator file and the birth section of the numerator (linked) file. 
Nonresidents are identified by a code 4 in location 11 of these files.
Demographic and Medical Classification
The documents listed below describe in detail the procedures employed for demographic
classification on both the birth and death records and medical classification on death records. 
While not absolutely essential to the proper interpretation of the data for a number of general
applications, these documents should nevertheless be studied carefully prior to any detailed
analysis of demographic or medical (especially multiple cause) data variables.  In particular,
there are a number of exceptions to the ICD rules in multiple cause-of-death coding which, if not
treated properly, may result in faulty analysis of the data.
A.   Manual of the International Statistical Classification of Diseases, Injuries, and the
     Cause-of-Death, Ninth Revision (ICD-9)  Volumes 1 and 2.
B.   NCHS Instruction Manual Data Preparation Part 2a, Vital Statistics Instructions for
     Classifying the Underlying Cause-of-Death.  Published annually.
C.   NCHS Instruction Manual Data Preparation, Part 2b, Vital Statistics Instructions for
     Classifying Multiple Cause-of-Death. Published annually.
D.   NCHS Instruction Manual Data Preparation, Part 2c, Vital Statistics ICD-9 ACME
     Decision Tables for Classifying Underlying Causes-of-Death.  Published annually.
E.   NCHS Instruction Manual Data Preparation, Part 2d, Vital Statistics NCHS Procedures
     for Mortality Medical Data System File Preparation and Maintenance, Effective 1985.
F.   NCHS Instruction Manual Data Tabulation, Part 2f, Vital Statistics ICD-9 TRANSAX
     Disease Reference Tables for Classifying Multiple Causes-of-Death, 1982-85.
G.   NCHS Instruction Manual Part 2g, Vital Statistics, Data Entry Instructions for the
     Mortality Medical Indexing, Classification, and Retrieval system (MICAR).  Published
     annually.
H.   NCHS Instruction Manual Part 2h, Vital Statistics, Dictionary of Valid Terms for the
     Mortality Medical Indexing, Classification, and Retrieval System (MICAR).  Published
     annually.
I.   NCHS Instruction Manual Data Preparation, Part 3a, Vital Statistics Classification and
     Coding Instructions for Live Birth Records.  Published annually.
J.   NCHS Instruction Manual Data Preparation, Part 4, Vital Statistics Demographic
     Classification and Coding Instructions for Death Records.  Published annually.
K.   NCHS Instruction Manual Tabulation, Part 11, Vital Statistics Computer Edits for
     Mortality Data, Effective 1990.
Copies of NCHS Instruction Manuals may be requested from the Chief, Data Preparation Branch,
Division of Data Processing, National Center for Health Statistics, P.O. Box 12214, Research
Triangle Park, North Carolina 27709.
In addition, the user should refer to the Technical Appendices of the Vital Statistics of the United
States for information on the source of data, coding procedures, quality of the data, etc.  The
Technical Appendices for natality and mortality are part of this documentation package.
Cause-of-Death Data
Mortality data are traditionally analyzed and published in terms of underlying cause-of-death. 
The underlying cause-of-death data are coded and classified as described in the Mortality
Technical Appendices.  NCHS has augmented underlying cause-of-death data with data on
multiple causes reported on the death certificate.  The linked file includes both underlying and
multiple cause-of-death data.
The multiple cause of death codes were developed with two objectives in mind.  First, to
facilitate etiological studies of the relationships among conditions, it was necessary to reflect
accurately in coded form each condition and its location on the death certificate in the exact
manner given by the certifier.  Secondly, coding needed to be carried out in a manner by which
the underlying cause of death could be assigned through computer applications.  The approach
was to suspend the linkage provisions of the ICD for the purpose of condition coding and code
each entity with minimum regard to other conditions present on the certification.  This general
approach is hereafter called entity coding.
Unfortunately, the set of multiple cause codes produced by entity coding is not conducive to a
third objective -- the generation of person-based multiple cause statistics.  Person-based analysis
requires that each condition be coded within the context of every other condition on the same
certificate and modified or linked to such conditions as provided by ICD-9.  By definition, the
entity data cannot meet this requirement since the linkage provisions distort the character and
placement of the information originally recorded by the certifying physician.
Since the two objectives are incompatible, NCHS has chosen to create from the original set of
entity codes a new code set called record axis multiple cause data.  Essentially, the axis of
classification has been converted from an entity basis to a record (or person)  basis.  The record
axis codes are assigned in terms of the set of codes that best describe the overall medical
certification portion of the death certificate.  
This translation is accomplished by a computer system called TRANSAX (translation of axis)
through selective use of traditional linkage and modification rules for mortality coding. 
Underlying cause linkages which simply prefer one code over another for purposes of underlying
cause selection are not included.  Each entity code on the record is examined and modified or
deleted as necessary to create a set of codes which are free of contradictions and are the most
precise within the constraints of ICD-9 and medical information on the record.  Repetitive codes
are deleted.  The process may (1) combine two entity axis categories together to a new category
thereby eliminating a contradiction or standardizing the data; or (2) eliminate one category in
favor of another to promote specificity of the data or resolve contradictions.  The following
examples from ICD-9 illustrate the effect of this translation:
          Case 1:   When reported on the same record as separate entities, cirrhosis of liver and
          alcoholism are coded to 5715 (cirrhosis of liver without mention of alcohol) and
          303 (alcohol dependence syndrome).  Tabulation of records with 5715 would on
          the surface falsely imply that such records had no mention of alcohol.  A
          preferable codification would be 5712 (alcoholic cirrhosis of liver) in lieu of both 
          5715 and 303.           
          Case 2:   If "gastric ulcer" and "bleeding gastric ulcer" are reported on a record they are
          coded to 5319 (gastric ulcer, unspecified as acute or chronic, without mention of
          hemorrhage or perforation) and 5314 (gastric ulcer, chronic or unspecified, with
          hemorrhage).  A more concise codification would be to code 5314 only since the
          5314 shows both the gastric ulcer and the bleeding.
Entity Axis Codes
The original conditions coded for selection of the underlying cause of death are reformatted and
edited prior to creating the public-use tape.  The following paragraphs describe the format and
application of entity axis data.
Format    
Each entity-axis code is displayed as an overall seven byte code with subcomponents
as follows:
1.  Line indicator:      The first byte represents the line of the certificate on which the
                         code appears.  Six lines (1-6) are allowable with the fourth and
                         fifth denoting one or two written in "due to"s beyond the three
                         lines provided in Part I of the U.S. standard death certificate.  Line
                         "6"  represents Part II of the certificate.
2.  Position indicator:  The next byte indicates the position of the code on the line, i.e., it
                         is the first (1), second (2), third (3),... eighth (8) code on the line.
3.  Cause category:      The next four bytes represent the ICD-9 cause code.
4.  Nature of injury flag:    ICD-9 uses the same series of numbers (800-999) to indicate nature
                              of injury (N codes) and external cause codes (E codes). This flag
                              distinguishes between the two with a one (1)  representing nature
                              of injury codes and a zero (0)  representing all other cause codes.
A maximum of 20 of these seven byte codes are captured on a record for multiple-cause
purposes.  This may consist of a maximum of 8 codes on any given line with up to 20 codes
distributed across three or more lines depending on where the subject conditions are located on
the certificate.  Codes may be omitted from one or more lines, e.g., line 1 with one or more
codes, line 2 with no codes, line 3 with one or more codes.
In writing out these codes, they are ordered as follows:  line 1 first code, line 1 second code, 
etc. ----- line 2 first code, line 2 second code, etc. ----- line 3  ----- line 4 ----- line 5 ----- 
line 6.  Any space remaining in the field is left blank.  The  specifics of locations are contained 
in the record layout given later in this document.
Edit   The original conditions are edited to remove invalid codes, reverify the coding of certain
rare causes of death, and assure age/cause and sex/cause compatibility.  Detailed information
relating to the edit criteria and the sets of cause codes which are valid to underlying cause coding
and multiple cause coding are provided in Part 11 of the NCHS Vital Statistics Instruction
Manual Series.   
Entity axis applications   The entity axis multiple cause data is appropriate to analyses which
require that each condition be coded as a stand alone entity without linkage to other conditions
and/or require information on the placement of such conditions in the certificate.   Within this
framework, the entity data are appropriate to the examination of etiological relationships among
conditions, accuracy of certification reporting, and the validity of traditional assumptions in
underlying cause selection.
Additionally, the entity data provide in certain categories a more detailed code assignment which
is linked out in the creation of record axis data.  Where such detail is needed for a study, the user
should selectively employ entity data.  Finally, the researcher may not wish to be bound by the
assumptions used in the axis translation process preferring rather to investigate hypotheses of his
own predilection.
By definition, the main limitation of entity axis data is that an entity code does not necessarily
reflect the best code for a condition when considered within the context of the medical
certification as a whole.  As a result certain entity codes can be misleading or even contradict
other codes in the record.  For example, category 5750 is titled "Acute cholecystitis without
mention of calculus".  Within the framework of entity codes this is interpreted to mean that the
codable entity itself contained no mention of calculus rather than that calculus was not mentioned
anywhere on the record.  Tabulation of records with a "5750"  as a count of persons having acute
cholecystitis without mention of calculus would therefore be erroneous.  This illustrates the fact
that under entity coding the ICD-9 titles cannot be taken literally.  The user must study the rules
for entity coding as they relate to his/her research prior to utilization of entity data.  The user is
further cautioned that the inclusion notes in ICD-9 which relate to modifying and combining
categories are seldom applicable to entity coding (except where provided in Part 2b of the Vital
Statistics Instruction Manual Series).                                            
In tabulating the entity axis data, one may count codes with the resultant tabulation of an
individual code representing the number of times the disease(s) represented by the code appears
in the file.  In this kind of tabulation of morbid condition prevalence, the counts among
categories may be added together to produce counts for groups of codes.  Alternatively, subject to
the limitations given above, one may count persons having mention of the disease represented by
a code or codes.  In this instance it is not correct to add counts for individual codes to create
person counts for groups of codes.  Since more than one code in the researcher's interest may
appear together on the certificate, totaling must account for higher order interactions among
codes.  Up to 20 codes may be assigned on a record; therefore, a 20-way interaction is
theoretically possible.  All totaling must be based on mention of one or more of the categories
under investigation.
Record Axis Codes
The following paragraphs describe the format and application of record-axis data.  Part 2f of the
Vital Statistics Instruction Manual Series describes the TRANSAX process for creating record
axis data from entity axis data.
Format   Each record (or person) axis code is displayed in five bytes.  Location information is
not relevant.  The Code consists of the following components:
                                 
 1.  Cause category:  The first four bytes represent the ICD-9 cause code.
 2.  Nature of injury flag:  The last byte contains a 0 or 1 with the 1 indicating that the cause
                             is a nature of injury category.
Again, a maximum of 20 codes are captured on a record for multiple cause purposes.  The codes
are written in a 100-byte field in ascending code number (5 bytes) order with any unused bytes
left blank.
Edit   The record axis codes are edited for rare causes and age/cause and sex/cause
compatibility.  Likewise, individual code validity is checked.  The valid code set for record axis
coding is the same as that for entity coding.
Record axis applications   The record axis multiple cause data set is the basis for NCHS core
multiple cause tabulations.  Location of codes is not relevant to this data set and conditions have
been linked into the most meaningful categories for the certification.  The most immediate
consequence for the user is that the codes on the record  already represent mention of a disease
assignable to that particular ICD-9 category.  This is in contrast to the entity code which is
assigned each time such a disease is reported on two different lines of the certification. 
Secondly, the  linkage implies that within the constraints of ICD-9 the most meaningful code has
been assigned.  The translation process creates for the user a data set which is edited for
contradictions, duplicate codes, and imprecisions.  In contrast to entity axis data, record axis data
are  classified in a manner comparable to underlying cause of death classification thereby
facilitating joint analysis of  these  variables.  Likewise, they are comparable to general morbidity
coding where the linkage provisions of ICD-9 are usually utilized.  A potential disadvantage of
record axis data is that some detail is sacrificed in a number of the linkages.
The user can take the record axis codes as literally representing the information conveyed in
ICD-9 category titles.  While knowledge of the rules for combining and linking and coding
conditions is useful, it is not a prerequisite to meaningful analysis of the data as long as one is
willing to accept the assumptions of the axis translation process. The user is cautioned, however,
that due to special rules in mortality coding, not all linkage notes in ICD-9 are utilized.  (See Part
2f of the Vital Statistics Instruction Manual Series.)
The user should proceed with caution in using record axis data to count conditions as opposed to
people with conditions since linkages have been invoked and duplicate codes have been
eliminated.  As with entity data, person based tabulations which combine individual cause
categories must take into account the possible interaction of up to 20 codes on a single certificate.
In using the NCHS multiple cause data, the user is urged to review the information in this
document and its references.  The instructional material does change from year to year and
revision to revision.  The user is cautioned that coding of specific ICD-9 categories should be
checked in the appropriate instruction manual.  What may appear on the surface to be the correct
code by ICD-9 may in fact not be correct as given in the instruction manuals.
If on the surface it is not obvious whether entity axis or record axis data should be employed in a
given application, detailed examination of Part 2f of the Vital Statistics Instruction Manual Series
and its attachments will probably provide the necessary information to make a decision.  It allows
the user to determine the extent of the trade-offs between the two sets of data in terms of specific
categories and the assumptions of axis translation.  In certain situations, a combination of entity
and record axis data may be the more appropriate alternative. 

Linked Birth/Infant Death Data Set:  1995 Period Data
Data File Characteristics:

     The data were processed using the SAS language on an IBM 9672.
     The data are recorded in IBM/EBCDIC 8-bit code for each character.
     Codes may be numeric, alphabets, or blank.
     The record type is blocked, fixed format.
     The last block for the data year may be a short block.
 
I.  Denominator File:
         United States Data Set 
     A.  File Organization:        One file, multiple tapes
     B.  Record count:             3,903,012
     C.  Record length:            210 
     D.  Blocksize:                32130
     E.  Data counts:   
            a. By occurrence:      3,903,012        
            b. By residence:         3,899,589
            c. To foreign residents:     3,423  
         
        Possessions Data Set
     A.  File Organization:        One file, one tape
     B.  Record count:             69,868
     C.  Record length:            210 
     D.  Blocksize:                32130
     Puerto Rico              
     Data counts:                  
          a. By occurrence:        63,518    
          b. By occurrence and
             residence:            63,419
          c. To foreign residents: 99
     Virgin Islands
      Data counts:          
          a. By occurrence:        2,164    
          b. By occurrence and 
             residence:            2,032
          c. To foreign residents: 132    
     Guam
     Data counts:                  
          a. By occurrence:        4,186   
          b. By occurrence and 
             residence:            4,180
          c. To foreign residents: 6  



Linked Birth/Infant Death Data Set:  1995 Period Data


II. Numerator File:
         United States Data Set 
     A.  File Organization:        One of multiple files on a tape
     B.  Record count:             28,767
     C.  Record length:            535 
     D.  Blocksize:                32635
     E.  Data counts:              
          a. By occurrence:        28,767
          b. By residence:         28,755   
          c. To foreign residents: 12  
         
        Possessions Data Set
     A.  File Organization:        one of multiple files on a tape
     B.  Record count:             863
     C.  Record length:            535 
     D.  Blocksize:                32635
     Puerto Rico
     Data counts:                  
         a. By occurrence:         797      
         b. By occurrence and 
            residence:             791
         c. To foreign residents:  6
     Virgin Islands
      Data counts:                 
         a. By occurrence:         29     
         b. By occurrence and 
            residence:             29
         c. To foreign residents:  0
     Guam
      Data counts:                 
         a. By occurrence:         37    
         b. By occurrence and 
            residence:             37  
         c. To foreign residents:  0

Linked Birth/Infant Death Data Set:  1995 Period Data


III. Unlinked  File:
         United States Data Set 
     A.  File Organization:        one file of multiple files on a tape
     B.  Record count:             750
     C.  Record length:            535 
     D.  Blocksize:                32635
     E.  Data counts:              
         a. By occurrence:         750
         b. By residence:          750  
         c. To foreign residents:  0  
         
        Possessions Data Set
     A.  File Organization:        one file of multiple files on a tape
     B.  Record count:             11
     C.  Record length:            535     
     D.  Blocksize:                32635
     Puerto Rico
     Data counts:             
         a. By occurrence:         10   
         b. By occurrence and 
            residence:             5
         c. To foreign residents:  5    
     Virgin Islands
      Data counts:                 
         a. By occurrence:         0     
         b. By occurrence and 
            residence:             0
         c. To foreign residents:  0    
     Guam
     Data counts:                  
         a. By occurrence:         1         
         b. By occurrence and 
            residence:             1
         c. To foreign residents:  0  



Geographic Code Outline
The following pages show the geographic codes used by the Division of Vital Statistics in the
processing of vital event data occurring in the United States.  For the linked data set, counties and
cities with a population of 250,000 or more are identified. 
Federal Information Processing Standards (FIPS) State, County, and City/Place Codes:  For the
1995 linked file, the county and city/place codes and the State code immediately preceding them
are FIPS codes.  These codes were effective with the 1994 data year and are based on the results
of the 1990 Census. County and county equivalents (independent and coextensive cities) are
numbered alphabetically within each State.  When an event occurs to a nonresident of the United
States, residence data are coded only to the "State" level, or to the remainder of the world.  For an
explanation of FIPS codes, reference should be made to various National Bureau of Standards
(NBS) publications.
1995
Denominator Record and Natality Section of Numerator (Linked) Record
   
Locations 7-210 of the linked file contain data from the Birth Certificate.
Locations 211-535 of linked file contain data from the Death Certificate.
Residence items in the Denominator Record and in the natality section of the Numerator 
(linked) Record refer to the usual place of residence of the Mother; whereas in the mortality 
section of the Numerator (Linked) Record, these items refer to the residence of the Decedent.
Item      Item           Variable Name,
Location  Length         Item and Code Outline
  1-6        6           R1
                         Reserved Positions
  7-10       4           BIRYR
                         Year of Birth
                           1994    ...  Born in 1994 (This code valid for numerator (linked) 
                                   file  file only).
                           1995    ...  Born in 1995
     
  11         1           RESSTATB
                         Resident Status - Birth
                                     
                         United States Occurrence 
                           1  ...  RESIDENTS:  State and county of occurrence and
                                   residence are the same.
                           2  ...  INTRASTATE NONRESIDENTS:  State of 
                                   occurrence and residence are the same, but county is 
                                   different.
                           3  ...  INTERSTATE NONRESIDENTS:  State of 
                                   occurrence and residence are different, but both are
                                   in the 50 States and D.C.
                           4  ...  FOREIGN RESIDENTS:  State of occurrence is one 
                                   of  the 50 States or the District of Columbia, but 
                                   place of  residence of mother is outside of the 50 
                                   States and D.C.
                         Puerto Rico Occurrence                       
                          1   ...  RESIDENTS: State and county of          
                                   occurrence and residence are the same.
                           2  ...  INTRASTATE NONRESIDENTS:  State of 
                                   occurrence and residence are the same, but county is 
                                   different.
                           4  ...  FOREIGN RESIDENTS: Occurred in Puerto Rico to
                                   a resident of any other place.
      
                         Virgin Islands Occurrence
                           1  ...  RESIDENTS: State and county of occurrence and
                                   residence are the same.
                           2  ...  INTRASTATE NONRESIDENTS:  State of 
                                   occurrence and residence are the same, but county is 
                                   different.
                           4  ...  FOREIGN RESIDENTS:  Occurred in the Virgin 
                                   Islands to a resident of any other place.
                         Guam Occurrence
                           1  ...  RESIDENTS: Occurred in Guam to a resident of
                                   Guam or to a resident of the U.S.
                           4  ...  FOREIGN RESIDENTS:  Occurred in Guam to a
                                   resident of any place other than Guam or of the U.S. 
Item      Item           Variable Name,
Location  Length         Item and Code Outline
12-13        2           BRSTATE
                         Expanded State of Residence - NCHS Codes - Birth
                           This item is designed to separately identify New York City records 
                         from other New York State records.           
                
                              
                           United States Occurrence    
                           01 ...  Alabama                  
                           02 ...  Alaska
                           03 ...  Arizona
                           04 ...  Arkansas
                           05 ...  California
                           06 ...  Colorado
                           07 ...  Connecticut
                           08 ...  Delaware
                           09 ...  District of Columbia
                           10 ...  Florida
                           11 ...  Georgia
                           12 ...  Hawaii
                           13 ...  Idaho
                           14 ...  Illinois
                           15 ...  Indiana
                           16 ...  Iowa
                           17 ...  Kansas
                           18 ...  Kentucky
                           19 ...  Louisiana
                           20 ...  Maine
                           21 ...  Maryland
                           22 ...  Massachusetts
                           23 ...  Michigan
                           24 ...  Minnesota
                           25 ...  Mississippi
                           26 ...  Missouri
                           27 ...  Montana
                           28 ...  Nebraska
                           29 ...  Nevada
                           30 ...  New Hampshire
                           31 ...  New Jersey
                           32 ...  New Mexico
                           33 ...  New York
                           34 ...  New York City
                           35 ...  North Carolina
                           36 ...  North Dakota
                           37 ...  Ohio
                           38 ...  Oklahoma
                           39 ...  Oregon
                           40 ...  Pennsylvania
                           41 ...  Rhode Island
                           42 ...  South Carolina
                           43 ...  South Dakota
                           44 ...  Tennessee
                           45 ...  Texas
                           46 ...  Utah
Item      Item           Variable Name,
Location  Length         Item and Code Outline
12-13       2            BRSTATE
                         Expanded State of Residence - NCHS Codes - Birth (Cond't)
                         This item is designed to separately identify New York City records 
                         from other  New York State records.                
                              
                           United States Occurrence    
                           47 ...  Vermont
                           48 ...  Virginia
                           49 ...  Washington
                           50 ...  West Virginia
                           51 ...  Wisconsin
                           52 ...  Wyoming
                           53, 58  ,60  ...  Foreign Residents
                           53      ...  Puerto Rico
                           54      ...  Virgin Islands
                           55      ...  Guam
                           56      ...  Canada
                           57      ...  Cuba
                           58      ...  Mexico
                           60      ...  Remainder of the World
                         Puerto Rico Occurrence
                           53      ...  Puerto Rico
                           01-52,54-58,60  ...    Foreign Residents:  Refer to U.S. for 
                                                  specific code structure.
                         Virgin Islands Occurrence
                           54      ...  Virgin Islands
                           01-53,55-58,60  ...    Foreign Residents:  Refer to U.S. for 
                                                  specific code structure. 
          
                         Guam Occurrence
                           55      ...  Guam
                           01-52        ...  U.S. resident is also considered a resident of
                                             Guam.
                           53,54,58,60  ...  Foreign Residents:  Refer to U.S. for 
                                             specific code structure. 
                         FIPSOCCB
                         Federal Information Processing Standards 
                         (FIPS) Geographic Codes (Occurrence) - Birth
                         Refer to the Geographic Code Outline further back  in this document 
                         for a detailed list of areas and  codes.  For an explanation of FIPS 
                         codes, reference should be made to various National Institute of 
                         Standards and Technology (NIST) publications.
                                
Denominator Record and Natality Section of Numerator (Linked) Record
                                
Item      Item           Variable Name,
Location  Length         Item and Code Outline
14-15       2            STOCCFIPB
                         State of Occurrence (FIPS) - Birth                               
                          United States 
                           01      ...  Alabama
                           02      ...  Alaska
                           04      ...  Arizona
                           05      ...  Arkansas
                           06      ...  California
                           08      ...  Colorado
                           09      ...  Connecticut
                           10      ...  Delaware
                           11      ...  District of Columbia
                           12      ...  Florida
                           13      ...  Georgia
                           15      ...  Hawaii
                           16      ...  Idaho
                           17      ...  Illinois
                           18      ...  Indiana
                           19      ...  Iowa
                           20      ...  Kansas
                           21      ...  Kentucky
                           22      ...  Louisiana
                           23      ...  Maine
                           24      ...  Maryland
                           25      ...  Massachusetts
                           26      ...  Michigan
                           27      ...  Minnesota
                           28      ...  Mississippi
                           29      ...  Missouri
                           30      ...  Montana
                           31      ...  Nebraska
                           32      ...  Nevada
                           33      ...  New Hampshire
                           34      ...  New Jersey
                           35      ...  New Mexico
                           36      ...  New York
                           37      ...  North Carolina
                           38      ...  North Dakota
                           39      ...  Ohio
                           40      ...  Oklahoma
                           41      ...  Oregon
                           42      ...  Pennsylvania
                           44      ...  Rhode Island
                           45      ...  South Carolina
                           46      ...  South Dakota
                           47      ...  Tennessee
                           48      ...  Texas

                           
Item      Item           Variable Name,
Location  Length         Item and Code Outline
14-15        2           STOCCFIPB
                         State of Occurrence (FIPS) - Birth (Cond't) 
                              
                          United States 
                           49      ...  Utah
                           50      ...  Vermont
                           51      ...  Virginia  
                           53      ...  Washington
                           54      ...  West Virginia
                           55      ...  Wisconsin
                           56      ...  Wyoming
                         Puerto Rico Occurrence        
                           72      ...  Puerto Rico
                         Virgin Islands Occurrence
                           78      ...  Virgin Islands
                         Guam Occurrence
                           66      ...  Guam
  16-18          3       CNTOCFIPB
                         County of Occurrence (FIPS) - Birth
                         001-nnn  ... Counties and county equivalents
                                      (independent and coextensive cities) are
                                      numbered alphabetically within each State.
                                      (Note:  To uniquely identify a county, both
                                      the State and county codes must be used.)
                         999      ... County with less than 250,000
                                      population
  19-23         5             FIPSRESB
                         Federal Information Processing Standards (FIPS) Geographic
                         Codes (Residence) - Birth
                          Refer to the Geographic Code Outline further back in this document 
                          for a  detailed list of areas and codes.  For an explanation of FIPS 
                          codes, reference  should be made to various National Institute of 
                          Standards and Technology  (NIST) publications.
                                
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  19-20          2            STRESFIPB
                         State of Residence (FIPS) - Birth
                              
                         United States Occurrence
                           00      ...  Foreign residents
                           01      ...  Alabama
                           02      ...  Alaska
                           04      ...  Arizona
                           05      ...  Arkansas
                           06      ...  California
                           08      ...  Colorado
                           09      ...  Connecticut
                           10      ...  Delaware
                           11      ...  District of Columbia
                           12      ...  Florida
                           13      ...  Georgia
                           15      ...  Hawaii
                           16      ...  Idaho
                           17      ...  Illinois
                           18      ...  Indiana
                           19      ...  Iowa
                           20      ...  Kansas
                           21      ...  Kentucky
                           22      ...  Louisiana
                           23      ...  Maine
                           24      ...  Maryland
                           25      ...  Massachusetts
                           26      ...  Michigan
                           27      ...  Minnesota
                           28      ...  Mississippi
                           29      ...  Missouri
                           30      ...  Montana
                           31      ...  Nebraska
                           32      ...  Nevada
                           33      ...  New Hampshire
                           34      ...  New Jersey
                           35      ...  New Mexico
                           36      ...  New York
                           37      ...  North Carolina
                           38      ...  North Dakota
                           39      ...  Ohio
                           40      ...  Oklahoma
                           41      ...  Oregon
                           42      ...  Pennsylvania
                           44      ...  Rhode Island
                           45      ...  South Carolina
                           46      ...  South Dakota
                           47      ...  Tennessee
                                
                               
Item      Item           Variable Name,
Location  Length              Item and Code Outline
19-20        2           STRESFIPB
                         State of Residence (FIPS) - Birth Cond't)
                              
                         United States Occurrence
                           48      ...  Texas
                           49      ...  Utah
                           50      ...  Vermont
                           51      ...  Virginia
                           53      ...  Washington
                           54      ...  West Virginia
                           55      ...  Wisconsin
                           56      ...  Wyoming
                         Puerto Rico Occurrence
                           00-56,66,78  ...  Foreign Residents:  Refer to U.S. for
                                             specific code structure
                           72      ...  Puerto Rico
                         Virgin Islands Occurrence
                           00-56,66,72  ...  Foreign Residents:  Refer to U.S. for
                                             specific code structure
                           78        ...     Virgin Islands
                         Guam Occurrence
                           00,72,78       ...     Foreign Residents:  Refer to U.S. for
                                                  specific code structure
                           01-56          ...     U.S. Resident is also considered a resident
                                                  of Guam.  Refer to U.S. for specific code
                                                  structure
                           66        ...     Guam
  21-23          3            CNTYRFPB
                         County of Residence (FIPS) - Birth
                           000          ...  Foreign residents
                           001-nnn ...  Counties and county equivalents
                                        (independent and coextensive cities) are
                                        numbered alphabetically within each State
                                        (Note:  To uniquely identify a county, both
                                        the State and county codes must be used.)
                           999          ...  County with less than 250,000 population
  24-28          5                 PLRES   
                         Place (City) of Residence (FIPS)
                         A complete list of cities is shown in the Geographic Code Outline 
                         further back  in this document.
                           00000             ...  Foreign residents
                           00001-nnnnn       ...  Code range
                           99999             ...  Balance of county; or city less than 
                                                  250,000  population
                                                             
 Item      Item           Variable Name,
Location  Length          Item and Code Outline
 29         1            MAGEFLG
                         Age of Mother Flag
                         This position is flagged whenever age is imputed or the mother's 
                         reported age is used.  The reported age is used, if valid, when
                         computed age derived from the date of birth is not available or when it is
                         outside the 10-49 code range.
                           Blank   ...  Not imputed and reported age is not used
                           1       ...  Reported age is used
                           2       ...  Age is imputed
 30-31      2            DMAGE
                         Age of Mother
                           This item is: a) computed using dates of birth of mother and of 
                           delivery; b) reported; or c) imputed. This is the age item used in 
                           NCHS publications.
                           10-49        ...  Age in single years
  32        1            MAGER8
                         Age of Mother Recode 8
                           1       ...  Under 15 years
                           2       ...  15 - 19 years
                           3       ...  20 - 24 years
                           4       ...  25 - 29 years
                           5       ...  30 - 34 years
                           6       ...  35 - 39 years
                           7       ...  40 - 44 years
                           8       ...  45 - 49 years
  33        1            ORMOTH
                         Hispanic Origin of Mother
                           Hispanic origin is reported for all areas except Puerto Rico.  
               
                           0       ...  Non-Hispanic
                           1       ...  Mexican
                           2       ...  Puerto Rican
                           3       ...  Cuban
                           4       ...  Central or South American
                           5       ...  Other and unknown Hispanic
                           9       ...  Origin unknown or not stated


Item      Item           Variable Name,
Location  Length              Item and Code Outline
  34        1            ORRACEM
                         Hispanic Origin and Race of Mother Recode
                           Hispanic origin is reported for all areas except  Puerto Rico. 
     
                           1       ...  Mexican
                           2       ...  Puerto Rican
                           3       ...  Cuban
                           4       ...  Central or South American
                           5       ...  Other and unknown Hispanic
                           6       ...  Non-Hispanic White
                           7       ...  Non-Hispanic Black
                           8       ...  Non-Hispanic other races
                           9       ...  Origin unknown or not stated
  35        1            MRACEIMP
                         Race of Mother Imputation Flag
                           Blank        ...  Race is not imputed
                           1       ...  Race is imputed
                           2       ...  All other races, formerly code 09, is imputed
36-37         2            MRACE
                         Race of Mother - Birth Record or for Unlinked Records Race of 
                         Decedent 
                         from Death Record
                              
                           Beginning with 1992 data, some areas started reporting additional 
                           Asian or Pacific Islander codes for race.  Codes 18-68 replace old 
                           code 08 for  these areas.  Code 78 replaces old code  08 for all other 
                           areas.  For consistency with Census race code 09 (all other races)
                           used prior to 1992 has been imputed.
  
                           United States Occurrence - Both Birth and Death
                            01          ...  White
                            02          ...  Black
                            03          ...  American Indian (includes Aleuts and 
                                             Eskimos)
                            04          ...  Chinese
                            05          ...  Japanese
                            06          ...  Hawaiian (includes part-Hawaiian)
                            07          ...  Filipino
                            18          ...  Asian Indian
                            28          ...  Korean
                            38          ...  Samoan
                            48          ...  Vietnamese
                            58          ...  Guamanian
                            68          ...  Other Asian or Pacific Islander in areas 
                                             reporting codes 18-58
                            78          ...  Combined other Asian or Pacific Islander, 
                                             includes  codes 18-68 for areas that do not 
                                             report them separately
Item      Item           Variable Name,
Location  Length              Item and Code Outline
36-37       2            MRACE
                         Race of Mother - Birth Record or for Unlinked Records Race of 
                         Decedent 
                         from Death Record (Cond't) 
                         Puerto Rico Occurrence - Birth
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander    
     
                         Puerto Rico Occurrence - Death
                           00      ...  Other races    
                           01      ...  White
                           02      ...  Black
                              
                         Virgin Islands Occurrence - Both Birth and Death
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander
                         Guam Occurrence - Both Birth and Death
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander
                           10      ...  Guamanian
  38        1            MRACE3
                         Race of Mother Recode
                           1       ...  White
                           2       ...  Races other than White or Black
                           3       ...  Black
Item      Item           Variable Name,
Location  Length              Item and Code Outline
39-40       2            DMEDUC
                         Education of Mother Detail 
                           All areas report education of mother.
                           00      ...  No formal education
                           01-08   ...  Years of elementary school
                           09      ...  1 year of high school
                           10      ...  2 years of high school
                           11      ...  3 years of high school
                           12      ...  4 years of high school
                           13      ...  1 year of college
                           14      ...  2 years of college
                           15      ...  3 years of college
                           16      ...  4 years of college
                           17      ...  5 or more years of college
                           99      ...  Not stated     
  41        1            MEDUC6
                         Education of Mother Recode
                           1       ...  0 - 8 years
                           2       ...  9 - 11 years
                           3       ...  12 years
                           4       ...  13 - 15 years
                           5       ...  16 years and over
                           6       ...  Not stated
  42        1            DMARIMP
                         Marital Status of Mother Imputation Flag
                           Blank        ...  Marital status is not imputed
                           1       ...  Marital status is imputed
  43        1            DMAR
                         Marital Status of Mother
                         Marital status is not reported by all areas.  See reporting flags.
                         United States/Virgin Islands/Guam Occurrence
                           1       ...  Married
                           2       ...  Unmarried
                           9       ...  Unknown or not stated
                         Puerto Rico Occurrence
                           1       ...  Married
                           2       ...  Unmarried parents living together
                           3       ...  Unmarried parents not living together
                           9       ...  Unknown or not stated                                    
                                       
Item      Item           Variable Name,
Location  Length          Item and Code Outline
44-45        2            MPLBIR
                          Place of Birth of Mother
                           01      ...  Alabama
                           02      ...  Alaska
                           03      ...  Arizona
                           04      ...  Arkansas
                           05      ...  California
                           06      ...  Colorado
                           07      ...  Connecticut
                           08      ...  Delaware
                           09      ...  District of Columbia
                           10      ...  Florida
                           11      ...  Georgia
                           12      ...  Hawaii
                           13      ...  Idaho
                           14      ...  Illinois
                           15      ...  Indiana
                           16      ...  Iowa
                           17      ...  Kansas
                           18      ...  Kentucky
                           19      ...  Louisiana
                           20      ...  Maine
                           21      ...  Maryland
                           22      ...  Massachusetts
                           23      ...  Michigan
                           24      ...  Minnesota
                           25      ...  Mississippi
                           26      ...  Missouri
                           27      ...  Montana
                           28      ...  Nebraska
                           29      ...  Nevada
                           30      ...  New Hampshire
                           31      ...  New Jersey
                           32      ...  New Mexico
                           33      ...  New York
                           34      ...  North Carolina
                           35      ...  North Dakota
                           36      ...  Ohio
                           37      ...  Oklahoma
                           38      ...  Oregon
                           39      ...  Pennsylvania
                           40      ...  Rhode Island
                           41      ...  South Carolina
                           42      ...  South Dakota
                           43      ...  Tennessee
                           44      ...  Texas
                           45      ...  Utah
                           46      ...  Vermont
                           47      ...  Virginia
                           48      ...  Washington
                           49      ...  West Virginia
                            
Item      Item           Variable Name,
Location  Length              Item and Code Outline
44-45        2            MPLBIR
                          Place of Birth of Mother (Cond't)
                           50      ...  Wisconsin
                           51      ...  Wyoming
                           52      ...  Puerto Rico
                           53      ...  Virgin Islands
                           54      ...  Guam
                           55      ...  Canada
                           56      ...  Cuba
                           57      ...  Mexico
                           59      ...  Remainder of the World
                           99      ...  Not Classifiable
  46        1            MPLBIRR
                         Place of Birth of Mother Recode
                         United States Occurrence
                           1       ...  Born in the 50 States and D.C.
                           2       ...  Born outside the 50 States and DC 
                           3       ...  Unknown or not stated
                         Puerto Rico/Virgin Island/ Guam Occurrence
                         Blank          ...  This item not recorded
 47-48        2          DTOTORD
                         Detail Total Birth Order
                           Sum of live birth order and other terminations of pregnancy.  If either 
                           item is  unknown, this item is made unknown.
                           01-40   ...  Total number of live births and other 
                                        terminations of  pregnancy
                           99      ...  Unknown 
49-50        2            DLIVORD
                         Detail Live Birth Order
 
                           00-31        ...  Number of children born alive to mother
                            99          ...  Unknown 
                                 
                     
Item      Item           Variable Name,
Location  Length              Item and Code Outline
51-52            2            MONPRE
                         Detail Month of Pregnancy Prenatal Care Began
                           00      ...  No prenatal care
                           01      ...  1st month
                           02      ...  2nd month
                           03      ...  3rd month
                           04      ...  4th month
                           05      ...  5th month
                           06      ...  6th month
                           07      ...  7th month
                           08      ...  8th month
                           09      ...  9th month
                           99      ...  Unknown or not stated
  53        1            MPRE5
                         Month Prenatal Care Began Recode 5
                           1       ...  1st Trimester (1st-3rd month)
                           2       ...  2nd Trimester (4th-6th month)
                           3       ...  3rd Trimester (7th-9th month)
                           4       ...  No prenatal care
                           5       ...  Unknown or not stated
  54-55          2            NPREVIST
                         Total Number of Prenatal Visits
                           00      ...  No prenatal visits
                           01-48        ...  Stated number of visits
                           49      ...  49 or more visits
                           99      ...  Unknown or not stated
  56        1            ADEQUACY
                         Adequacy of Care Recode (Kessner Index)
                     This code is based on a modified Kessner criterion. Month Prenatal 
                          Care Began,  Number of Prenatal Visits, and Gestation are the items 
                          used to generate this  recode.
                           1       ...  Adequate
                           2       ...  Intermediate
                           3       ...  Inadequate
                           4       ...  Unknown
     
  57-59          3            DISLLB
                         Interval Since Last Live Birth
                      This item was computed using date of birth of the child and date of 
                           last live birth.
                           777          ...  No previous live birth
                           000          ...  Zero months (plural birth)
                           001-468 ...  One to four hundred sixty-eight
                                        months
                           999     ...  Unknown
                             
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  60        1            FAGERFLG
                         Reported Age of Father Used Flag
                           This position is flagged whenever the Father's reported age in years is 
                           used.  The reported age is used, if valid, when age derived from date 
                           of birth is not available or when it is less than 10.
                           Blank        ...  Reported age is not used
                           1       ...  Reported age is used
 61-62       2            DFAGE
                         Age of Father
                           This item is either computed from date of  birth of father and of child 
                           or is the  reported age.  This is the age item used in NCHS     
                           publications.
                           10-98        ...  Age in single years
                           99      ...  Unknown or not stated
  63        1            ORFATH
                         Hispanic Origin of Father
                           Hispanic origin is reported for all areas except  Puerto Rico. 
     
                           0       ...  Non-Hispanic
                           1       ...  Mexican
                           2       ...  Puerto Rican
                           3       ...  Cuban
                           4       ...  Central or South American
                           5       ...  Other and unknown Hispanic
                           9       ...  Origin unknown or not stated
  64        1            ORRACEF
                         Hispanic Origin and Race of Father Recode
                           Hispanic origin is reported for all areas except  Puerto Rico. 
     
                           1       ...  Mexican
                           2       ...  Puerto Rican
                           3       ...  Cuban     
                           4       ...  Central or South American
                           5       ...  Other and unknown Hispanic
                           6       ...  Non-Hispanic White
                           7       ...  Non-Hispanic Black
                           8       ...  Non-Hispanic other or unknown
                                        race
                           9       ...  Origin unknown or not stated


Item      Item           Variable Name,
Location  Length              Item and Code Outline
65-66        2           FRACE
                         Race of Father
                      Beginning with 1992 data, some areas started reporting additional 
                           Asian or Pacific Islander codes for race.  See reporting flags.  Codes 
                           18 -68 replace old  code 08 for these areas.  Code 78 replaces old
                           code 08 for all other areas.  Code 09 (all other races) has been changed to 
                           99.
                           United States Occurrence    
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts 
                                        and Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           18      ...  Asian Indian
                           28      ...  Korean
                           38      ...  Samoan
                           48      ...  Vietnamese
                           58      ...  Guamanian
                           68      ...  Other Asian or Pacific Islander 
                                        in areas reporting codes 18-58
                           78      ...  Combined other Asian or Pacific Islander, 
                                        includes codes 18-68 for areas that do not 
                                        report them  separately
                           99      ...  Unknown or not stated
                
                           Puerto Rico Occurrence
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander
                    
                         Virgin Islands Occurrence
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander
                 
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  65-66          2            FRACE
                         Race of Father  (Cond't)
                         Guam Occurrence
                           01      ...  White
                           02      ...  Black
                           03      ...  American Indian (includes Aleuts and 
                                        Eskimos)
                           04      ...  Chinese
                           05      ...  Japanese
                           06      ...  Hawaiian (includes part-Hawaiian)
                           07      ...  Filipino
                           08      ...  Other Asian or Pacific Islander
                           10      ...  Guamanian
67          1            PLDEL
                         Place or Facility of Delivery 
                             1          ...  Hospital 
                             2          ...  Freestanding Birthing Center
                             3          ...  Clinic or Doctor's Office
                             4          ...  A Residence
                             5          ...  Other
                             9          ...  Unknown or Not Stated
68          1            BIRATTND
                         Attendant at Delivery
                           1       ...  Doctor of Medicine (M.D.)
                           2       ...  Doctor of Osteopathy (D.O.)
                           3       ...  Certified Nurse Midwife (C.N.M.)
                           4       ...  Other Midwife
                           5       ...  Other
                           9       ...  Unknown or not stated
69          1            R2
                         Reserved position
70          1            GESTESTM
                         Clinical Estimate of Gestation Used Flag
                         This position is flagged whenever the clinical estimate of gestation is 
                         used.  It is used when gestation could not be computed or when the 
                         computed gestation is outside the 17-47 code range.
                           Blank   ...  Clinical Estimate is not used
                           1       ...  Clinical Estimate is used
Item      Item           Variable Name,
Location  Length              Item and Code Outline
71-72          2              CLINGEST
                         Clinical Estimate of Gestation
                           Clinical estimate is not reported by all areas. 
                           See reporting flags.
                           17-47        ...  Estimated gestation in weeks
                           99      ...  Unknown or not stated
 73         1            GESTIMP
                         Gestation Imputation Flag
                           Blank        ...  Gestation is not imputed
                           1       ...  Gestation is imputed
  74-75          2            GESTAT
                         Gestation - Detail in Weeks
                         This item is: a) computed using dates of birth of child and last normal 
                         menses; b)  imputed from LMP date; c) the clinical estimate; or d) 
                         unknown when there is  insufficient data to impute or no valid clinical 
                         estimate.  This is the gestation  item used in NCHS publications.
                           17-47        ...  17th through 47th week of gestation
                           99      ...  Unknown
  76-77          2            GESTAT 10
                         GESTATION RECODE 10
                           01      ...  Under 20 weeks
                           02      ...  20 - 27 weeks
                           03      ...  28 - 31 weeks
                           04      ...  32 - 35 weeks
                           05      ...  36 weeks
                           06      ...  37 - 39 weeks
                           07      ...  40 weeks
                           08      ...  41 weeks
                           09      ...  42 weeks and over
                           10      ...  Not stated
  78        1            CSEXIMP
                         Sex Imputation Flag
                           Blank        ...  Sex is not imputed
                           1       ...  Sex is imputed
  79        1            CSEX
                         Sex
                           1       ...  Male
                           2       ...  Female

Item      Item           Variable Name,
Location  Length              Item and Code Outline
  80-87        8              BIRTHWEIGHT
                         Beginning in 1995, an imputation for not-stated birthweight was added 
                         to reduce potential bias in the data (see section on Changes beginning 
                         with the 1995 data year in the introductory text to this documentation). 
                         The following imputation flag can be used to delete imputed values for 
                         those researchers wishing to use only reported birthweight data.
  80      1              BWIF
                         Birth Weight Imputation Flag 
               
                           Blank        ...  Birthweight is not imputed
                           1       ...  Birthweight is imputed
  81-84          4            DBIRWT
                         Birth Weight Detail in Grams (Imputed)
                           0227-8165    ...  Number of grams
                           9999         ...  Not stated birth weight 
  85-86          2            BIRWT12
                         Birth Weight Recode 12 (Imputed)
                           
                           01      ...  499 grams or less
                           02      ...  500-999 grams
                           03      ...  1000-1499 grams
                           04      ...  1500-1999 grams
                           05      ...  2000-2499 grams
                           06      ...  2500-2999 grams
                           07      ...  3000-3499 grams
                           08      ...  3500-3999 grams
                           09      ...  4000-4499 grams
                           10      ...  4500-4999 grams
                           11      ...  5000-8165 grams
                           12      ...  Unknown or not stated
  87             1            BIRWT4
                         Birth Weight Recode 4 (Imputed)
                           1       ...  1499 grams or less
                           2       ...  1500-2499 grams
                           3       ...  2500 grams or more
                           4       ...  Unknown or not stated
  88        1            PLURIMP
                         Plurality Imputation Flag
                           Blank        ...  Plurality is not imputed
                           1       ...  Plurality is imputed
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  89        1            DPLURAL
                         Plurality
                           1       ...  Single
                           2       ...  Twin
                           3       ...  Triplet
                           4       ...  Quadruplet
                           5       ...  Quintuplet or higher
  90-91          2            FMAPS
                         Five-Minute Apgar Score
                         Apgar score is not reported by all areas.  See reporting flags.
                           00-10        ...  A score of 0-10
                           99      ...  Unknown or not stated
  92-186         95       MEDINFO
                         Medical and Health Data
                          Some States do not report an entire item while other States do not 
                          report all of  the categories within an item.  If an item is not reported, 
                          it is indicated by code zero in the appropriate reporting flag.  If a 
                          category within an item is not  reported it is indicated by code 8 in the  
                          position for that category.
 92-99          8         DELMETH
                         Method of Delivery
                           Each method is assigned a separate position, and the code structure
                           for each  method (position) is:
                           1       ...  The method was used
                           2       ...  The method was not used
                           8       ...  Method not on certificate
                           9       ...  Method unknown or not stated
  92        1            VAGINAL
                         Vaginal
  93        1            VBAC
                         Vaginal Birth After Previous C-Section
  94        1            PRIMAC
                         Primary C-Section
  95        1            REPEAC
                         Repeat C-Section
  96        1            FORCEP
                         Forceps


Item      Item           Variable Name,
Location  Length              Item and Code Outline
  97        1            VACUUM
                         Vacuum
  98        1            R3
                         Reserved Position
  99        1            DELMETH5
                         Method of Delivery Recode
                           1       ...  Vaginal (excludes Vaginal after previous C-
                                        section)
                           2       ...  Vaginal birth after previous C section
                           3       ...  Primary C-section
                           4       ...  Repeat C-Section
                           5       ...  Not stated
 100-117    18           MEDRISK
                         Medical Risk Factors
                           Each risk factor is assigned a separate position, and the code structure
                           for  each risk factor (position) is:
                           1       ...  Factor reported
                           2       ...  Factor not reported
                           8       ...  Factor not on certificate
                           9       ...  Factor not classifiable
  100       1              MRFLAG
                         No Medical Risk Factors Reported Flag
                           Blank   ...  One or more medical risk factors coded,
                                        one, eight, or nine
                           2       ...  No medical risk factors reported.  Each 
                                        factor is coded a two.
  101       1            ANEMIA
                         Anemia (Hct.<30/Hgb.<10)
  102       1            CARDIAC
                         Cardiac disease
  103       1            LUNG
                         Acute or chronic lung disease
  104       1            DIABETES
                         Diabetes
  105       1            HERPES
                         Genital herpes
  106       1            HYDRA
                         Hydramnios/Oligohydramnios

   
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  107       1            HEMO
                         Hemoglobinopathy
  108       1            CHYPER
                         Hypertension, chronic
  109       1            PHYPER
                         Hypertension, pregnancy-associated
  110       1            ECLAMP
                         Eclampsia
  111       1            INCERVIX
                         Incompetent cervix
  112       1            PRE4000
                         Previous infant 4000+ grams
  113       1            PRETERM
                         Previous preterm or small-for-gestational-age infant
  114       1            RENAL
                         Renal disease
  115       1            RH
                         Rh sensitization
  116       1            UTERINE
                         Uterine bleeding
  117       1            OTHERMR
                         Other Medical Risk Factors 
  118-128   11           OTHERRSK
                         Other Risk Factors for this Pregnancy
  118-121   4            TOBACRSK
                         Tobacco Risks
  118       1            TOBACCO
                         Tobacco Use During Pregnancy
                           1       ...  Yes
                           2       ...  No
                           9       ...  Unknown or not stated
 119-120    2            CIGAR
                         Average Number of Cigarettes Per Day
                           00-97        ...  As stated
                           98      ...  98 or more cigarettes per day
                           99      ...  Unknown or not stated
  
Item      Item           Variable Name,
Location  Length              Item and Code Outline
 121        1            CIGAR6
                         Average Number of Cigarettes Per Day Recode
                           0       ...  Nonsmoker
                           1       ...  1-5 cigarettes per day
                           2       ...  6-10 cigarettes per day
                           3       ...  11-20 cigarettes per day
                           4       ...  21-40 cigarettes per day
                           5       ...  41 or more cigarettes per day
                           6       ...  Unknown or not stated
122-125     4            ALCOHRSK
                         Alcohol
122         1            ALCOHOL
                         Alcohol Use During Pregnancy
                           1       ...  Yes
                           2       ...  No
                           9       ...  Unknown or not stated
123-124     2            DRINK
                         Average Number of Drinks Per Week
                           00-97        ...  As stated
                           98      ...  98 or more drinks per week
                           99      ...  Unknown or not stated
125         1            DRINK5
                         Average Number of Drinks Per Week Recode
                           0       ...  Non drinker
                           1       ...  1 drink per week
                           2       ...  2 drinks per week
                           3       ...  3-4 drinks per week
                           4       ...  5 or more drinks per week
                           5       ...  Unknown or not stated
  126-128   3            WTGANRSK
                         Weight Gain During Pregnancy
  126-127   2            WTGAIN
                         Weight Gain
                           00-97        ...  Stated number of pounds
                           98      ...  98 pounds or more
                           99      ...  Unknown or not stated
Item      Item           Variable Name,
Location  Length         Item and Code Outline
128         1            WTGAIN9
                         Weight Gain Recode
                           1       ...  Less than 16 pounds
                           2       ...  16-20 pounds
                           3       ...  21-25 pounds
                           4       ...  26-30 pounds
                           5       ...  31-35 pounds
                           6       ...  36-40 pounds
                           7       ...  41-45 pounds
                           8       ...  46 or more pounds
                           9       ...  Unknown or not stated
129-136     8            OBSTETRC
                         Obstetric Procedures
                          Each procedure is assigned a separate position, and the code structure 
                         for each  procedure (position) is:
                           1       ...  Procedure reported
                           2       ...  Procedure not reported
                           8       ...  Procedure not on certificate
                           9       ...  Procedure not classifiable
 129        1            OBFLAG
                         Obstetric Flag
                         Blank     ...  One or more obstetric procedures coded, 
                                        one, eight, or nine
                         2         ...  No obstetric procedures reported.  Each 
                                        factor is  coded a two.
  130       1            AMNIO
                         Amniocentesis
  131       1            MONITOR
                         Electronic fetal monitoring
  132       1            INDUCT
                         Induction of labor
  133       1            STIMULA
                         Stimulation of labor
  134       1            TOCOL
                         Tocolysis
  135       1            ULTRAS
                         Ultrasound
  136       1            OTHEROB
                         Other Obstetric Procedures
 Item      Item           Variable Name,
Location  Length          Item and Code Outline
137-153     17           LABOR
                         Complications of Labor and/or Delivery
                         Each complication is assigned a separate position, and the code
                         structure for each complication (position) is:
                           1       ...  Complication reported
                           2       ...  Complication not reported
                           8       ...  Complication not on certificate
                           9       ...  Complication not classifiable
  137       1            FBFLAG
                         Labor Flag
                           Blank   ...  One or more labor and/or delivery  
                                        complication
                                        coded, one, eight, or nine
                           2       ...  No labor and/or delivery complication 
                                        reported.
                                        Each factor is coded a two.
  138       1            FEBRILE
                         Febrile (>100 degrees F. or 38 degrees C.) 
  139       1            MECONIUM
                         Meconium, moderate/heavy
  140       1            RUPTURE
                         Premature rupture of membrane (>12 hours) 
  141       1            ABRUPTIO
                         Abruptio placenta
  142       1            PREPLACE
                         Placenta previa
  143       1            EXCEBLD
                         Other excessive bleeding
  144       1            SEIZURE
                         Seizures during labor
  145       1            PRECIP
                         Precipitous labor (<3 hours) 
  146       1            PROLONG
                         Prolonged labor (>20 hours)
  147       1            DYSFUNC
                         Dysfunctional labor
  148       1            BREECH
                         Breech/Malpresentation


Item      Item           Variable Name,
Location  Length              Item and Code Outline
  149       1            CEPHALO
                         Cephalopelvic disproportion
  150       1            CORD
                         Cord prolapse
  151       1            ANESTHE
                         Anesthetic complications
  152       1            DISTRESS
                         Fetal distress
                                
  153       1            OTHERLB
                         Other Complication of Labor and/or Delivery
154-163     10           NEWBORN
                         Abnormal conditions of the Newborn
                           Each condition is assigned a separate position, and
                           the code structure for each condition (position)is:
                           1       ...  Condition reported
                           2       ...  Condition not reported
                           8       ...  Condition not on certificate
                           9       ...  Condition not classifiable
 154        1            NBFLAG
                         Newborn Flag
                           Blank   ...  One or more abnormal conditions of the
                                        newborn coded, one, eight, or nine
                           2       ...  No abnormal condition of the newborn
                                        reported.  Each factor is coded a two.   
  155       1            NANEMIA
                         Anemia Hct.>39/Hgb.<13)
  156       1            INJURY
                         Birth injury
  157       1            ALCOSYN
                         Fetal alcohol syndrome
  158       1            HYALINE
                         Hyaline membrane disease
  159       1            MECONSYN
                         Meconium aspiration syndrome
  160       1            VENL30
                         Assisted ventilation, less than 30 minutes

                              
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  161       1            VEN30M
                         Assisted ventilation, 30 minutes or more
  162       1            NSEIZ
                         Seizures
  163       1            OTHERAB
                         Other Abnormal Conditions of the Newborn
 164-186    23           CONGENIT
                         Congenital Anomalies
                           Each anomaly is assigned a separate position, and the code structure
                           for each anomaly (position) is:
                           1       ...  Anomaly reported
                           2       ...  Anomaly not reported
                           8       ...  Anomaly not on certificate
                           9       ...  Anomaly not classifiable
 164      1              CGFLAG
                         Congenital Flag
                           Blank   ...  One or more congenital anomaly coded, one,
                                             eight, or nine
                           2       ...  No congenital anomaly is reported.  Each
                                        factor is coded a two.
  165       1            ANEN
                         Anencephalus
  166       1            SPINA
                         Spina bifida/Meningocele
  167       1            HYDRO
                         Hydrocephalus
  168       1            MICROCE
                         Microcephalus
  169       1            NERVOUS
                         Other central nervous system anomalies
  170       1            HEART
                         Heart malformations
  171       1            CIRCUL
                         Other circulatory/respiratory anomalies
  172       1            RECTAL
                         Rectal atresia/stenosis


Item      Item           Variable Name,
Location  Length              Item and Code Outline
  173       1            TRACHEO
                         Tracheo-esophageal fistula/Esophageal atresia
  174       1            OMPHALO
                         Omphalocele/Gastroschisis
  175       1            GASTRO
                         Other gastrointestinal anomalies
  176       1            GENITAL
                         Malformed genitalia
  177       1            RENALAGE
                         Renal agenesis
  178       1            UROGEN
                         Other urogenital anomalies
  179       1            CLEFTLP
                         Cleft lip/palate
  180       1            ADACTYLY
                         Polydactyly/Syndactyly/Adactyly
  181       1            CLUBFOOT
                         Club foot
  182       1            HERNIA
                         Diaphragmatic hernia
  183       1            MUSCULO
                         Other musculoskeletal/integumental anomalies
  184       1            DOWNS
                         Down's syndrome
  185       1            CHROMO
                         Other chromosomal anomalies
  186       1            OTHERCON
                         Other congenital anomalies
 187-203    17           FLRES
                         Reporting Flags for Place of Residence
                         These positions contain flags to indicate whether or not the specified
                         item isincluded on the birth certificate of the State of residence or of the
                         SMSA of residence.   The code structure of each flag (position) is:
                           0       ...  The item is not reported
                           1       ...  The item is reported or partially reported.


Item      Item           Variable Name,
Location  Length              Item and Code Outline
  187       1            ORIGM
                         Origin of mother
  188       1            ORIGF
                         Origin of father
  189       1            EDUCM
                         Education of mother
  190       1            R4
                         Reserved Position
  191       1            GESTE
                         Clinical estimate of gestation
  192       1            R5
                         Reserved position
                              
  193       1            FMAPSRF
                         5-minute Apgar score
  194       1            DELMETRF
                         Method of delivery
  195       1            MEDRSK
                         Medical risk factors
  196       1            TOBUSE
                         Tobacco use
  197       1            ALCUSE
                         Alcohol use
  198       1            WTGN
                         Weight gain
  199       1            OBSTRC
                         Obstetric procedures
  200       1            CLABOR
                         Complications of labor and/or delivery
  201       1            ABNML
                         Abnormal conditions of newborn
  202       1            CONGAN
                         Congenital anomalies
 
  203       1            API flag
                         Race codes 18-68 reported (beginning with 1992 data)


Item      Item           Variable Name,
Location  Length         Item and Code Outline
 204                    CDOBMIMP
                         Month of Birth of Child Imputation Flag
                           Blank        ...  Month is not imputed
                           1       ...  Month is imputed
  205-206   2            BIRMON
                         Month of Birth
                           01      ...  January
                           02      ...  February
                           03      ...  March
                           04      ...  April
                           05      ...  May
                           06      ...  June
                           07      ...  July
                           08      ...  August
                           09      ...  September
                           10      ...  October
                           11      ...  November
                           12      ...  December            
          
  207-208   2            R6
                         Reserved Position
          
  209       1            WEEKDAYB
                         Day of Week Child Born
                           1       ...  Sunday
                           2       ...  Monday
                           3       ...  Tuesday
                           4       ...  Wednesday
                           5       ...  Thursday
                           6       ...  Friday
                           7       ...  Saturday
  210       1            FLGND
                         Flag Indicating Records Included in Both Numerator and
                         Denominator Files
                         This variable is included in the denominator files only, and identifies
                         a record which is also included in the numerator file.  Please note that not all
                         infant deaths in the numerator file are represented in the denominator file,
                         because some of the infants who died in 1995 were born in 1994.
                           1       ...  Record also included in numerator file
                           Blank   ...  Record not included in numerator file

Here ends the Denominator file.  Documentation for the Mortality Section of the Numerator (Linked) file 
begins on the next page.

                             
1995 Mortality Section of  Numerator (Linked) Record
Locations 211-535 contain data from the Death Certificate. Residence items in the Denominator Record
and in the natality section of the Numerator (Linked) Record refer to the usual place of residence of the
Mother; whereas in the mortality section of the Numerator (Linked) Record, these items refer to the place
of residence of the Decedent.
Item      Item           Variable Name,
Location  Length         Item and Code Outline
 211-213    3            AGED
                         Age at Death in Days
                         The generated age at death in days is calculated from the date of death
                         on the death certificate minus the date of birth on the birth certificate unless
                         the reported age of death is less than 2 days, then the reported age is used. 
                         If the exact date of birth and/or death is unknown, the age is imputed.
                           000-364 ...  Number of days
  214       1            AGER5
                         Infant Age Recode 5
                           1       ...  Under 1 hour
                           2       ...  1-23  hours
                           3       ...  1-6   days                   
                           4       ...  7-27 days (late neonatal)
                           5       ...  28 days and over (postneonatal)
  215       1            ACCIDPL
                         Place of Accident for Causes E850-E869 and E880-E928
                           Blank        ...  Causes other than E850-E869 and E990-
                                             E928
                           0       ...  Home
                           1       ...  Farm
                           2       ...  Mine and quarry
                           3       ...  Industrial place and premises
                           4       ...  Place for recreation and sport
                           5       ...  Street and highway
                           6       ...  Public building
                           7       ...  Resident institution
                           8       ...  Other specified places
                           9       ...  Place of accident not specified
  216-219   4            UCOD
                         ICD Code (9th Revision)
                         See the International Classification of Diseases, 1975 Revision,
                         Volume 1.  For injuries and poisoning, the external cause is coded (E800-E999)
                         rather than the Nature of Injury (800-899).  These positions do not include
                         the letter E for the external cause of injury.  For those causes that do not have a
                         4th digit, location 219 is blank.


Item      Item           Variable Name,
Location  Length         Item and Code Outline
220-222      3            UCODR61
                          61 Infant Cause Recode
                           A recode of the ICD cause code into 61 groups for NCHS
                           publications.  Further back in this document is a complete list of recodes and the causes
                           included.
                           010-680 ...  Code range (not inclusive)
223-230      8            RECWT
                          Record weight
                          Beginning in 1995, a record weight was added to the  linked file to
                          adjust for the approximately 2-3% of  records each year which cannot be linked to
                          their corresponding birth certificates (see introduction to this tape
                          documentation for further details).  These weights are used to produce all NCHS linked
                          file tables, including Documentation tables 1-5 included in this tape
                          documentation. The general format for this record weight is the number one followed by a
                          decimal point and six decimal places as follows:
                           1.XXXXXX

Item      Item           Variable Name,
Location  Length         Item and Code Outline
 61-504    244           MULTCOND
                         Multiple Conditions
                    See the "International Classification of Diseases", 
                         1975 Revision, Volume 1. 
                         Both the entity-axis and record-axis conditions are coded according to
                         this revision (9th).
 261-262   2             EANUM
                         Number of Entity-Axis Conditions
                           00-20        ...  Code range
 263-402  140            ENTITY
                         ENTITY - AXIS CONDITIONS
                         Space has been provided for a maximum of 20 conditions.  Each
                         condition takes 7 positions in the record.  
                         Records that do not have 20 conditions are blank in the unused area.
                           Position 1:  Part/line number on certificate
                           1       ...  Part I,  line 1 (a)
                           2       ...  Part I,  line 2 (b)
                           3       ...  Part I,  line 3 (c)
                           4       ...  Part I,  line 4 (d)
                           5       ...  Part I,  line 5 (e)
                           6       ...  Part II,  
                           Position 2:  Sequence of condition within part/line
                           1-7     ...  Code range
                           Position 3 - 6:   Condition code (ICD 9th Revision)
                           Position 7:  Nature of Injury Flag
                           1       ...  Indicates that the code in positions 3-6 is a
                                        Nature of 
                                        Injury code
                           0       ...  All other codes
  263-269   7            1st Condition
  270-276   7            2nd Condition
  277-283   7            3rd Condition
  284-290   7            4th Condition
  291-297   7            5th Condition


                               
Item      Item           Variable Name,
Location  Length              Item and Code Outline
  298-304   7            6th Condition
  305-311   7            7th Condition
  312-318   7            8th Condition 
  319-325   7            9th Condition
  326-332   7            10th Condition
  333-339   7            11th Condition
  340-346   7            12th Condition
  347-353   7            13th Condition
  354-360   7            14th Condition
  361-367   7            15th Condition
  368-374   7            16th Condition
  375-381   7            17th Condition
  382-388   7            18th Condition
  389-395   7            19th Condition
  396-402   7            20th Condition
                         RANUM
  403-404   2            Number of Record-Axis Conditions
                           00-20   ...  Code range
  405-504   100               RECORD
                         RECORD - AXIS CONDITIONS
                         Space has been provided for a maximum of 20 conditions.  Each
                         condition takes 5 positions in the record.  
                         Records that do not have 20 conditions are blank in the unused area.
                           Positions 1-4:    Condition code (ICD 9th Revision)
                           Position 5:  Nature of Injury Flag
                           1       ...  Indicates that the code in positions 1-4 is a
                                        Nature of Injury code
                           0       ...  All other codes
Item      Item           Variable Name,
Location  Length         Item and Code Outline
  405-409   5            1st Condition
  410-414   5            2nd Condition
  405-419   5            3rd Condition
  420-424   5            4th Condition
  425-429   5            5th Condition
  430-434   5            6th Condition
  435-439   5            7th Condition
  440-444   5            8th Condition
  445-449   5            9th Condition
  450-454   5            10th Condition
  455-459   5            11th Condition
  460-464   5            12th Condition
  465-469   5            13th Condition
  470-474   5            14th Condition
  475-479   5            15th Condition
  480-484   5            16th Condition
  485-489   5            17th Condition
  490-494   5            18th Condition
  495-499   5            19th Condition
  500-504   5            20th Condition
                                   
  505             1           RESSTATD
                         Resident Status - Death
                         United States Occurrence 
                           1  ...  RESIDENTS:  State and county of occurrence and
                                   residence  are the same.
                           2  ...  INTRASTATE NONRESIDENTS:  State of
                                   occurrence and residence are the same, but county is
                                   different.
                           3  ...  INTERSTATE NONRESIDENTS:  State of
                                   occurrence and residence are different, but both are
                                   in the 50 States and D.C.
                           4  ...  FOREIGN RESIDENTS:  State of occurrence is one
                                   of the 50 States or the District of Columbia, but place
                                   of residence is outside of the 50 States and D.C.
Item      Item           Variable Name,
Location  Length         Item and Code Outline
  505        1           RESSTATD
                         Resident Status - Death (Cond't)
                         Puerto Rico Occurrence
                           1  ...  RESIDENTS: State and county of occurrence and
                                   residence are the same.
                           2  ...  INTRASTATE NONRESIDENTS:  State of
                                   occurrence and residence are the same, but county is
                                   different.
                           4  ...  FOREIGN RESIDENTS: Occurred in Puerto Rico to
                                   a resident of any other place.
      
                         Virgin Islands Occurrence
                           1       ...  RESIDENTS: State and county of
                                        occurrence and residence are the same.
                           2       ...  INTRASTATE NONRESIDENTS:  State of
                                        occurrence and residence are the same, but
                                        county is different.
                           4       ...  FOREIGN RESIDENTS:  Occurred in the
                                        Virgin Islands to a resident of any other
                                        place.
                         Guam Occurrence
                           1       ...  RESIDENTS: Occurred in Guam to a
                                        resident of Guam or to a resident of the U.S.
                           4       ...  FOREIGN RESIDENTS:  Occurred in
                                        Guam to a resident of any place other than
                                        Guam or  the U.S. 
 
  506-507 2              DRSTATE
                         Expanded State of Residence - NCHS Codes - Deaths
                         This item is designed to separately identify New York City records 
                         from other   New York State records.
                           United States Occurrence
                           01      ...  Alabama
                           02      ...  Alaska
                           03      ...  Arizona
                           04      ...  Arkansas
                           05      ...  California
                           06      ...  Colorado
                           07      ...  Connecticut
                           08      ...  Delaware
                           09      ...  District of Columbia
                           10      ...  Florida
                           11      ...  Georgia
                           12      ...  Hawaii
                           13      ...  Idaho
                           14      ...  Illinois
                           15      ...  Indiana
                           16      ...  Iowa
                           17      ...  Kansas
                           18      ...  Kentucky
                           19      ...  Louisiana
                           20      ...  Maine
                  
Item      Item           Variable Name,
Location  Length              Item and Code Outline
 506-507    2            DRSTATE
                         Expanded State of Residence - NCHS Codes - Deaths (Cond't)  
                         
                           United States Occurrence
                           21      ...  Maryland
                           22      ...  Massachusetts
                           23      ...  Michigan
                           24      ...  Minnesota
                           25      ...  Mississippi
                           26      ...  Missouri
                           27      ...  Montana
                           28      ...  Nebraska
                           29      ...  Nevada
                           30      ...  New Hampshire
                           31      ...  New Jersey
                           32      ...  New Mexico
                           33      ...  New York
                           34      ...  New York City
                           35      ...  North Carolina
                           36      ...  North Dakota
                           37      ...  Ohio
                           38      ...  Oklahoma
                           39      ...  Oregon
                           40      ...  Pennsylvania
                           41      ...  Rhode Island
                           42      ...  South Carolina
                           43      ...  South Dakota
                           44      ...  Tennessee
                           45      ...  Texas
                           46      ..   Utah
                           47      ...  Vermont
                           48      ...  Virginia
                           49      ...  Washington
                           50      ...  West Virginia
                           51      ...  Wisconsin
                           52      ...  Wyoming
                           53-58,60     ...  Foreign Residents
                           53      ...  Puerto Rico
                           54      ...  Virgin Islands
                           55      ...  Guam
                           56      ...  Canada
                           57      ...  Cuba
                           58      ...  Mexico
                           60      ...  Remainder of the World
                         Puerto Rico Occurrence
                           53      ...  Puerto Rico
                           01-52,54-58,60    ...  Foreign Residents:  Refer to U.S. for 
                                                  specific code structure.     

Technical Appendix - 1994 Natality File
Definition of live birth 
Every product of conception that gives a sign of life after birth, regardless of the length of
the pregnancy, is considered a live birth.  This concept is included in the definition set forth by
the World Health Organization (1): 
Live birth is the complete expulsion or extraction from its mother of a product of   
conception, irrespective of the duration of pregnancy, which, after such separation, breathes or
shows any other evidence of life, such as beating of the heart, pulsation of the umbilical cord, or
definite movement of voluntary muscles, whether or not the umbilical cord has been cut or the
placenta is attached; each product of such a birth is considered liveborn. 
This definition distinguishes in precise terms a live birth from a fetal death (see the
section on fetal deaths in the Technical Appendix of volume II, Vital Statistics of the United
States). In the interest of comparable natality statistics, both the Statistical Commission of the
United Nations and the National Center for Health Statistics (NCHS) have adopted this definition
(2,3).
History of birth-registration area 
The national birth-registration area was proposed in 1850 and established in 1915. By
1933 all 48 States and the District of Columbia were participating in the registration system. The
organized territories of Hawaii and Alaska were admitted in 1929 and 1950, respectively; data
from these areas were prepared separately until they became States--Alaska in 1959 and Hawaii
in 1960. Currently the birth-registration system of the United States covers the 50 States, the
District of Columbia, the independent registration area of New York City, Puerto Rico, the U.S.
Virgin Islands, Guam, American Samoa, and the Commonwealth of the Northern Mariana
Islands. However, in the statistical tabulations, ``United States'' refers only to the aggregate of the
50 States (including New York City) and the District of Columbia. 
The original birth-registration area of 1915 consisted of 10 States and the District of
Columbia. The growth of this area is indicated in table 4-1. This table also presents for each year
through 1932 the estimated midyear population of the United States and of those States included
in the registration system. 
Because of the growth of the area for which data have been collected and tabulated, a
national series of geographically comparable data before 1933 can be obtained only by
estimation. Annual estimates of births have been prepared by P. K. Whelpton for 1909-34 (4).
These estimates include adjustments for underregistration  and for States that were not part of the
birth-registration area before 1933. 
Sources of data 
Natality statistics 

Since 1985 natality statistics for all States and the District of Columbia have been based
on information from the total file of records. The information is received on computer data tapes
coded by the States and provided to NCHS through the Vital Statistics Cooperative Program.
NCHS receives these tapes from the registration offices of all States, the District of Columbia,
and New York City. Information for PuertoRico is also received on computer tapes through the
Vital Statistics Cooperative Program. Information for the Virgin Islands and Guam is obtained
from microfilm copies of original birth certificates and is based on the total file of records for all
years.
Birth statistics for years prior to 1951 and for 1955 are based on the total file of birth records.
Statistics for 1951-54, 1956-66, and 1968-71 are based on 50-percent samples except for data for
Guam and the Virgin Islands, which are based on all records filed. During the processing of the 1967
data the sampling rate was reduced from 50 percent to 20 percent. For details of this procedure and
its consequences for the 1967 data see pages 3-9 to 3-11 in volume I of Vital Statistics of the United
States, 1967. From 1972 to 1984 statistics are based on all records filed in the States submitting
computer tapes and on a 50-percent sample of records in all other States.
Information for years prior to 1970 for Puerto Rico, the Virgin Islands, and Guam is
published in the annual vital statistics reports of the Department of Health of the Commonwealth of
Puerto Rico, the Department of Public Health of the Virgin Islands, the Department of Public Health
and Social Services of the Government of Guam, and in selected Vital Statistics of the United States
annual reports.
U.S. natality data are limited to births occurring within the United States, including those
occurring to U.S. residents and nonresidents.  Births to nonresidents of the United States have been
excluded from all tabulations by place of residence beginning in 1970 (for further discussion see
``Classification by occurrence and residence''). Births occurring to U.S. citizens outside the United
States are not included in any tabulations in this report. Similarly the data for Puerto Rico, the Virgin
Islands, and Guam are limited to births registered in these areas. 
Standard certificate of live birth 
The U.S. Standard Certificate of Live Birth, issued by the Public Health Service, has served
for many years as the principal means of attaining uniformity in the content of the documents used
to collect information on births in the United States. It has been modified in each State to the extent
required by the particular State's needs or by special provisions of the State's vital statistics law.
However, most State certificates conform closely in content to the standard certificate.
The first standard certificate of birth was developed in 1900. Since then, it has been revised
periodically by the national vital statistics agency through consultation with State health officers and
registrars; Federal agencies concerned with vital statistics; national, State, and county medical
societies; and others working in public health, social welfare, demography, and insurance. This
procedure has assured careful evaluation of each item for its current and future usefulness for
legal, medical, demographic, and research purposes. New items have been added when necessary,
and old items have been modified to ensure better reporting or, in some cases, dropped when their
usefulness appeared to be limited. 
1989 revision--Effective January 1, 1989, a revised U.S. Standard Certificate of Live Birth
(figure 4-A) replaced the 1978 revision. This revision provided a wide variety of new information
on maternal and infant health characteristics, representing a significant departure from previous
versions in both content and format. The most significant format change was the use of checkboxes
to obtain detailed medical and health information about the mother and child. It has been
demonstrated that this format produces higher quality and more complete information than do
open-ended items.
The reformatted items included ``Medical Risk Factors for This Pregnancy,'' which combines
the former items ``Complications of Pregnancy'' and ``Concurrent Illnesses or Conditions Affecting
the Pregnancy.'' ``Complications of  Labor and/or Delivery'' and ``Congenital Anomalies of Child'' 
also have been revised from the open-ended format. For each of these items at least 15 specific
conditions have been identified. 
Several new items were added to the revised certificate. Included are items to obtain
information on tobacco and alcohol use during pregnancy, weight gain during pregnancy, obstetric
procedures, method of delivery, and abnormal conditions of the newborn. These items can be used
to monitor the health practices of the mother that can affect pregnancy and the use of technology in
childbirth, and to identify babies with specific abnormal conditions. When combined with other
socioeconomic and health data, these items provide a wealth of information relevant to the etiology
of low birthweight and other adverse pregnancy outcomes. 
Another modification was the addition of a Hispanic identifier for the mother and father.
Although NCHS had recommended that States add items to identify the Hispanic or ethnic origin
of the newborn's parents, concurrent with the 1978 revision of the U.S. Standard Certificate of Live
Birth and reported data from the cooperating States since that year, the item was new to the U.S.
Standard Certificate for 1989. 
The 1989 revised certificate also provided more detail than previously requested on the birth
attendant and place of birth. This permits a more in-depth analysis of the number and characteristics
of births by attendant and type of facility and a comparison of differences in outcome. For further
discussion see individual sections for each item. 
Classification of data 
One of the principal values of vital statistics data is realized through the presentation of rates
that are computed by relating the vital events of a class to the population of a similarly defined class.
Vital statistics and population statistics, therefore, must be classified according to similarly defined
systems and tabulated in comparable groups. Even when the variables common to both, such as
geographic area, age, race, and sex, have been similarly classified and tabulated, differences between
the enumeration method of obtaining population data and the registration method of obtaining vital
statistics data may result in significant discrepancies.
The general rules used to classify geographic and personal items for live births are set forth
in ``Vital Statistics Classification and Coding Instructions for Live Birth Records, 1994,'' NCHS
Instruction Manual, Part 3a. The classification of certain important items is discussed in the
following pages. 
Classification by occurrence and residence 
Births to U.S. residents occurring outside this country are not reallocated to the United States.
In tabulations by place of residence, births occurring within the United States to U.S. citizens and
to resident aliens are allocated to the usual place of residence of the mother in the United States, as
reported on the birth certificate. Beginning in 1970 births to nonresidents of the United States
occurring in the United States are excluded from these tabulations. From 1966 to 1969 births
occurring in the United States to mothers who were nonresidents of the United States were
considered as births to residents of the exact place of occurrence; in 1964 and 1965 all such births
were allocated to ``balance of county'' of occurrence even if the birth occurred in a city. The change
in coding beginning in 1970 to exclude births to nonresidents of the United States from residence
data significantly affects the comparability of data with years before 1970 only for Texas. 
For the total United States the tabulations by place of residence and by place of occurrence
are not identical. Births to nonresidents of the United States are included in data by place of
occurrence but excluded from data by place of residence, as previously indicated. 
Residence error--A nationwide test of birth-registration completeness in 1950 provided measures of
residence error for natality statistics. According to this test, errors in residence reporting for the
country as a whole tend to overstate the number of births to residents of  urban areas and to
understate the number of births to residents of other areas. This tendency has assumed special
importance because of a concomitant development--the increased utilization of hospitals in cities by
residents of nearby places--with the result that a number of births are erroneously reported as having
occurred to residents of urban areas. Another factor that contributes to this overstatement of urban
births is the customary procedure of using ``city'' addresses for persons living outside the city limits.
Incomplete residence--Beginning in 1973 where only the State of residence is reported with no city
or county specified and the State named is different from the State of occurrence, the birth is
allocated to the largest city of the State of residence. Before 1973 such births were allocated to the
exact place of occurrence. 

Geographic classification 
The rules followed in the classification of geographic areas for live births are contained in
the instruction manual mentioned previously. The geographic code structure for 1994 is given in
another
manual, ``Vital Records Geographic Classification, 1982,'' NCHS Instruction Manual , Part 8. 
United States--In the statistical tabulations, ``United States'' refers only to the aggregate of the 50
States and the District of Columbia. Alaska has been included in the U.S. tabulations since
1959 and Hawaii since 1960. 
Metropolitan statistical areas--The metropolitan statistical areas and primary metropolitan statistical
areas (MSA's and PMSA's) used in this report are those established by the U.S. Office of
Management and Budget as of April 1, 1990, and used by the U.S. Bureau of the Census (5) except
in the New England States. 
Except in the New England States, an MSA has either a city with a population of at least
50,000, or a Bureau of the Census urbanized area of at least 50,000 and a total MSA population of
at least 100,000. A PMSA consists of a large urbanized county, or cluster of counties, that
demonstrates very strong internal economic and social links and has a population over 1 million.
When PMSA's are defined, the large area of which they are component parts is designated a
Consolidated Metropolitan Statistical Area (CMSA) (6).
In the New England States the U.S. Office of Management and Budget uses towns and cities
rather than counties as geographic components of MSA's and PMSA's. NCHS cannot, however, use
this classification for these States because its data are not coded to identify all towns. Instead, the
New England County Metropolitan Areas (NECMA's) are used. These areas are established by the
U.S. Office of Management and Budget (7) and are made up of county units.
Metropolitan and nonmetropolitan counties-- Independent cities and counties included in
MSA's and PMSA's or NECMA's are included in data for metropolitan counties; all other counties
are classified as nonmetropolitan.
Population-size groups--Beginning in 1994 vital statistics data for cities and certain other urban
places have been classified according to the population enumerated in the 1990 Census of
Population. Data are available for individual cities and other urban places of 10,000 or more
population. Data for the remaining areas not separately identified are shown in the tables under the
heading ``Balance of area'' or ``Balance of county.'' Classification of areas for 1982-93 was
determined by the population enumerated in the 1980 Census of Population. As a result of changes
in the enumerated population between 1980 and 1990, some urban places identified in previous
reports are no longer included, and a number of other urban places have been added.
Urban places other than incorporated cities for which vital statistics data are shown in this
report include the following: 
     Each town in New England, New York, and Wisconsin and each township in Michigan, New
     Jersey, and Pennsylvania that had no incorporated municipality as a subdivision and had
     either 25,000 inhabitants or more, or a population of 10,000 to 25,000 and a density of 1,000
     persons or more per square mile. 
     Each county in States other than those indicated above that had no incorporated municipality
     within its boundary and had a density of 1,000 persons or more per square mile. (Arlington
     County, Virginia, is the only county classified as urban under this rule.) 
     Each place in Hawaii with 10,000 or more population. (There are no incorporated cities in
     Hawaii.) 
Race or national origin 
Beginning with the 1989 data year birth data are tabulated primarily by race of mother. In
1988 and prior years the race or national origin shown in tabulations was that of the newborn child.
The race of the child was determined for statistical purposes by an algorithm based on the race of
the mother and father as reported on the birth certificate.  When the parents were of the same race,
the race of the child was the same as the race of the parents. When the parents were of different races
and one parent was white, the child was assigned to the race of the other parent. When the parents
were of different races and neither parent was white, the child was assigned to the race of the father,
with one exception--if either parent was Hawaiian, the child was assigned to Hawaiian. If race was
missing for one parent, the child was assigned the race of the parent for whom it was reported. When
information on race was missing for both parents, the race of the child was considered not stated and
the birth was allocated according to rules discussed on page 4 of the Technical Appendix, volume
I, Vital Statistics of the United States, 1988. In 1989 the criteria for reporting the race of the parents
did not change and continues to reflect the response of the informant (usually the mother).
The most important factor influencing the decision to tabulate births by race of the mother
was the decennial revision of the U.S. Standard Certificate of Live Birth in 1989. This revision
included many more health questions that are directly associated with the mother, including alcohol
and tobacco use, weight gain during pregnancy, medical risk factors, obstetric procedures,
complications of labor and/or delivery, and method of delivery. Additionally, many of the other
items that have been on the birth certificate for more than two decades also relate directly to the
mother, for example, marital status, education level, and receipt of prenatal care. It is more
appropriate to use the race of the mother than the race of the child in tabulating these items. 
A second factor has been the increasing incidence of interracial parentage. In 1994, 4.4
percent of births were to parents of different races, compared with just 1.7 percent in 1974. About
half of these births were to white mothers and fathers of another race. There have been two major
consequences of the increasing interracial parentage. One is the effect on birth rates by race. The
number of white births under the former procedures has been arbitrarily limited to infants whose
parents were both white (or one parent if the race of only one parent was reported). At the same time,
the number of births of other races has been arbitrarily increased to include all births to white
mothers and fathers of other races. Thus, prior to 1989, if race of mother had been used, birth rates
per 1,000 white women in a given age group would have been higher, while comparable rates for
black women and women of other races would have been lower. The other consequence of
increasing interracial parentage is the impact on the racial differential in various characteristics of
births, particularly in cases where there is generally a large racial disparity, such as the incidence of
low birthweight. In this instance, the racial differential is larger when the data are tabulated by race
of mother rather than by race of child.  The same effect has been noted for characteristics such as
nonmarital childbearing, preterm births, late or no prenatal care, and low educational attainment of
mother.
The third factor influencing the change is the growing proportion of births with race of father
not stated, 16 percent in 1994 compared with 9 percent in 1974. This reflects the increase in the
proportion of births to unmarried women; in many cases no information is reported on the father.
These births were already assigned the race of the mother on a de facto basis. Tabulating births by
race of mother provides a more uniform approach, rather than a necessarily arbitrary combination
of parental races.
The change in the tabulation of births by race presents some problems when analyzing birth
data by race, particularly trend data.  The problem is likely to be acute for races other than white and
black.  
The categories for race or national origin are ``White,'' ``Black,'' ``American Indian''
(including Aleuts and Eskimos), ``Chinese,'' ``Japanese,'' ``Hawaiian,'' ``Filipino,'' and ``Other Asian
or Pacific Islander'' (including Asian Indian). Before 1992 there was also an ``other'' category, which
is now combined with the ``Not stated'' category. Before 1978 the category ``Other Asian or Pacific
Islander'' was not identified separately but included with ``Other'' races. The separation of this
category allows
identification of the category ``Asian or Pacific Islander'' by combining the new category ``Other
Asian or Pacific Islander'' with Chinese, Japanese, Hawaiian, and Filipino.
The category ``White'' comprises births reported as white and births where race is reported
as Hispanic. Before 1964 all births for which race or national origin was not stated were classified
as white.  Beginning in 1964 changes in the procedures for allocating race when race or national
origin is not stated have changed the composition of this category. (See discussion on ``Race or
national origin not stated.'')
If the race or national origin of an Asian parent is ill-defined or not clearly identifiable with
one of the categories used in the classification (for example, if ``Oriental'' is entered), an attempt is
made to determine the specific race or national origin from the entry for place of birth. If the
birthplace is China, Japan, or the Philippines, the race of the parent is assigned to that category.
When
race cannot be determined from birthplace, it is assigned to the category ``Other Asian or Pacific
Islander.'' 
Race or national origin not stated--If the race of the mother is not defined or not identifiable with one
of the categories used in the classification and the race of the father is known, the race of the father
is assigned to the mother. Where information for both parents is missing, the race of the mother is
allocated electronically according to the specific race of the mother on the preceding record with a
known race of mother. Data for both parents were missing for only 0.5 percent of birth certificates
for 1994.  Nearly all statistics by race or national origin for the United States as a whole in 1962 and
1963 are affected by a lack of information for New Jersey, which did not report the race of the
parents in those years. Birth rates by race for those years are computed on a population base that
excluded New Jersey. For the method of estimating the U.S. population by age, sex, and race
excluding New Jersey in 1962 and 1963, see page 4-8 in the Technical Appendix of volume I, Vital
Statistics of the United States, 1963. 
Beginning in 1992, NCHS contracted with seven States with the highest API populations to
code births to additional API subgroups.  The API subgroups include births to Vietnamese, Asian
Indian, Korean, Samoan, Guamanian, and other API women.  The seven States included in this
reporting area are: California, Hawaii, Illinois, New Jersey, New York, Texas, and Washington.  At
least two-thirds of the U.S. population of each of these additional API groups lived in the seven-State
reporting area(8).  The data are available on the detailed natality tapes and CD-ROMs beginning with
the 1992 data year.  An analytic report based on the 1992 data year is also available upon request(9). 
   
Age of mother 
Beginning in 1989 an item on the birth certificate asks for ``Date of Birth.'' In previous years,
``Age (at time of this birth)'' was requested. Not all States have revised this item for 1989, and
therefore the age of mother either is derived from the reported month and year of birth or coded as
stated on the certificate. The age of mother is edited for upper and lower limits. When the age of
mother is computed to be under 10 years or 50 years or over, it is considered not stated and is
assigned as described below.
Age-specific birth rates are based on populations of women by age, prepared by the U.S.
Bureau of the Census. In census years the decennial census counts are used. In intercensal years,
estimates of the population of women by age are published by the U.S. Bureau of the Census in
Current Population Reports.  
The 1990 Census of Population derived age in completed years as of April 1, 1990, from the
responses to questions on age at last birthday and month and year of birth, with the latter given
preference. In the 1960, 1970, and the 1980 Census of Population, age was also derived from month
and year of birth. ``Age in completed years'' was asked in censuses before 1960. This was nearly the
equivalent of the former birth certificate question, which the 1950 test of matched birth and census
records confirms by showing a high degree of consistency in reporting age in these two sources (10). 
Median age of mother--Median age is the value that divides an age distribution into two equal parts,
one-half of the values being less and one-half being greater. Median ages of mothers for 1960 to the
present have been computed from birth rates for 5-year age groups rather than from birth frequencies.
This method eliminates the effects of changes in the age composition of the childbearing population
over time. Changes in the median ages from year to year can thus be attributed solely to changes in
the age-specific birth rates.
Not stated date of birth of mother--Beginning in 1964 birth records with date of birth of mother
and/or age of mother not stated have had age imputed according to the age of mother from the
previous birth record of the same race and total-birth order (total of fetal deaths and live births). (See
``Vital Statistics Computer Edits for Natality Data,'' NCHS Instruction Manual , Part 12, page 9.)
In 1963 birth records with age not stated were allocated according to the age appearing on the record
previously processed for a mother of identical race and parity (number of live births). For 1960-62
not stated ages were distributed in proportion to the known ages for each racial group. Before 1960
this was done for age-specific birth rates but not for the birth frequency tables, which showed a
separate category for age not stated. 
Age of father 
Age of father is derived from the reported date of birth or coded as stated on the birth
certificate. If the age is under 10 years, it is considered not stated and grouped with those cases for
which age is not stated on the certificate. Information on age of father is often missing on birth
certificates of children born to unmarried mothers, greatly inflating the number of ``not stated'' in all
tabulations by age of father. In computing birth rates by age of father, births tabulated as age of father
not stated are distributed in the same proportions as births with known age within each 5-year-age
classification of the mother. This procedure is done separately by race. The resulting distributions
are summed to form a composite frequency distribution that is the basis for computing birth rates
by age of father. This procedure avoids the distortion in rates that would result if the relationship
between age of mother and age of father were disregarded. 
Live-birth order and parity 
Live-birth order and parity classifications shown in this volume refer to the total number of
live births the mother has had including the 1994 birth. Fetal deaths are excluded.
Live-birth order indicates what number the present birth represents; for example, a baby born
to a mother who has had two previous live births (even if one or both are not now living) has a
live-birth order of three. Parity indicates how many live births a mother has had.  Before delivery a
mother having her first baby has a parity of zero and a mother having her third baby has a parity of
two. After delivery the mother of a baby who is a first live birth has a parity of one and the mother
of a baby who is a third live birth has a parity of three.  
Live-birth order and parity are determined from two items on the birth certificate, ``Live
births now living'' and ``Live births now dead.''
Not stated birth order--Before 1969 if both of these items were blank, the birth was considered a first
birth. Beginning in 1969, births for which the pregnancy history items were not completed have
been tabulated as live-birth order not stated. As a result of this revised procedure, 22,686 births in
1969 that would have been assigned to the ``First birth order'' category under the old rules were
assigned to the ``Not stated'' category.
All births tabulated in the ``Not stated birth order'' category are excluded from the
computation of percents. In computing birth rates by live-birth order, births tabulated as birth order
not stated are distributed in the same proportion as births of known live-birth order.
Date of last live birth 
The date of last live birth was added to the U.S. Standard Certificate of Live Birth in 1968
for the purpose of providing information on child spacing. The interval since the last live birth is
the difference between the date of last live birth and the date of present birth. For an interval to be
computed, both the month and year of the last live birth must be valid. This interval is computed
only for events to mothers who have had at least one previous live birth.
Births for which the interval since last live birth is not stated are excluded from the
computation of percents and means.
Zero interval--An interval of zero months since the last live birth indicates the second born of a set
of twins, the second or third born of a set of triplets, and so forth. Births with an interval of zero
months are excluded from the computation of mean intervals. 
Educational attainment 
Data on the educational attainment of both parents were collected beginning in 1968 and
tabulated for publication in 1969 for the first time. 
The educational attainment of either parent is defined as ``the number of years of school
completed.'' Only those years completed in ``regular'' schools are counted, that is, a formal
educational system of public schools or the equivalent in accredited private or parochial schools.
Business or trade schools, such as beauty and barber schools, are not considered ``regular'' schools
for the purposes of this item.  No attempt has been made to convert years of school completed in
foreign school systems, ungraded school systems, and so forth, to equivalent grades in the American
school system. Such entries are included in the category ``Not stated.''
Persons who have completed only a partial year in high school or college are tabulated as
having completed the highest preceding grade.  For those certificates on which a specific degree is
stated, years of school completed is coded to the level at which the degree is most commonly
attained; for example, persons reporting B.A., A.B., or B.S. degrees are considered to have
completed 16 years of school.
Education not stated--The category ``Not stated'' includes all records in reporting areas for which
there is no information on years of school completed as well as all records for which the information
provided is not compatible with coding specifications.  Births tabulated as education not stated are
excluded from the computations of percents. 
Marital status 
Beginning with 1980 data, national estimates of births to unmarried women are derived from
two sources. In 1994 marital status was reported directly on the birth certificates of 45 States and the
District of Columbia. In the remaining five States, which lack such an item (California, Connecticut,
Michigan, Nevada, and New York), marital status is inferred from a comparison of the child's and
parents' surnames. This procedure represents a substantial departure from the method used before
1980 to prepare national estimates of births to unmarried women, which assumed that the incidence
of births to unmarried women in States with no direct question on marital status was the same as the
incidence in reporting States in the same geographic division.
The current method uses related information on the birth certificate to improve the quality
of national data on this topic, as well as to provide data for the individual nonreporting States.
Beginning in 1980 a birth in a nonreporting State is classified as occurring to a married woman if
the parents' surnames are the same, or if the child's and father's surnames are the same and the
mother's current surname cannot be obtained from the informant item of the birth certificate. A birth
is classified as occurring to an unmarried woman if the father's name is missing, if the parents'
surnames are different, or if the father's and child's surnames are different and the mother's current
surname is missing.
Because of the continued substantial increases in nonmarital childbearing throughout the
1980's, the data have been intensively evaluated in each year, 1985-94. There has been continuing
concern that the current method might overstate the number of births to unmarried women because
it incorporates data based on a comparison of surnames. This is because births to women who have
retained their maiden surname as their legal surname after marriage and who are frequently older,
well-educated women, would be classified as nonmarital births.  Trends based on data incorporating
inferential statistics can be compared with trends based on the geographic estimates for the 1980-94
period to show the impact of the two methods.  The trends for the two methods are similar for all
races combined and for white and black births.  Between 1980 and 1994, birth rates for unmarried
white women increased 112 percent based on data incorporating inferential information and 116
percent based on the geographic estimates.  Birth rates for unmarried black women increased 1
percent based on the inferential data and declined 2 percent based on geographic estimates. 
Michigan and Texas births--The number of births to unmarried women in Michigan was
underreported during the years 1988-93, but the greatest undercount, numerically, was for 1990-93. 
Michigan had separate counts of the numbers of births with paternity acknowledgments, but did not 
include them with the counts of unmarried women based on the general inferential procedures that
were provided to NCHS.  The underreporting began in 1988, and was about 25 percent for the years
1988-93.  In 1993 NCHS reported 36,326 births to unmarried women in Michigan, 26 percent below
the number that included paternity affidavits (49,281) (11).  Thus, there is a considerable
discontinuity in the nonmarital birth data for Michigan from 1993 to 1994.  The proportion of
nonmarital births reported to NCHS increased from 26 percent to 35 percent.  
The number of births to unmarried women in Texas was underreported during the years
1989-93.  As a result of legislation passed in 1989, a birth was considered to have occurred to a
married woman if the mother provides any information about the father, or if a paternity affidavit
has been filed.  The measurement of marital status for Texas births improved beginning with the
1994 data year because a direct question on marital status was added to the Texas birth certificate. 
However, there is a considerable discontinuity in the data for Texas from 1993 to 1994.  The
proportion of births to unmarried mothers increased from 17 to 29 percent.  
No adjustments are made during the data processing for errors in the reporting of marital
status on the birth records of the 45 reporting States and the District of Columbia because the extent
of this reporting problem is unknown. When marital status is not stated on the birth certificate of a
reporting area, the mother is considered married.
When births to unmarried women are reported as second- or higher-order births, it is not
known whether the mother was married or unmarried when the previous deliveries occurred, because
her marital status at the time of these earlier births is not available from the birth record.
Rates for 1940 and 1950 are based on decennial census counts. Rates for 1955-94 are based
on a smoothed series of population estimates (12). Because of sampling error, the original U.S.
Bureau of the Census population estimates by marital status fluctuate erratically from year to year;
therefore, they have been smoothed so that the rates do not show similar variations. These rates differ
from those published in volumes of Vital Statistics of the United States before 1969, which were
based on the original estimates provided annually by the U.S. Bureau of the Census. Birth rates by
marital status for 1971-79 have been revised and differ from rates published before 1980 in volumes
of Vital Statistics of the United States (see ``Computation of rates and other measures'').
Place of delivery and attendant at birth 
The 1989 revision of the U.S. Standard Certificate of Live Birth included separate categories
for freestanding birthing centers, the mother's residence, and clinic or doctor's office as the place of
birth. Prior to 1989, place of birth was classified simply as either ``In hospital'' or ``Not in hospital.''
Births occurring in hospitals, institutions, clinics, centers, or homes were included in the category
``In hospital.'' In this context the word ``homes'' does not refer to the mother's residence but to an
institution, such as a home for unmarried women. Birthing centers were included in either category,
depending on each State's assessment of the facility.  Beginning in 1989 births occurring in clinics
and in birthing centers not attached to a hospital are classified as ``Not in hospital.''  This change in
classification may account in part for the lower proportion of ``In hospital'' births compared with
previous years.  (The change in classification of clinics should have minor impact
because comparatively few births occur in these facilities, but the effect of any change in
classification of freestanding birthing centers is unknown.)
Beginning in 1975 the attendant at birth and place of delivery items were coded
independently, primarily to permit the identification of the person in attendance at hospital
deliveries. The 1989 certificate includes separate classifications for ``M.D.'' (Doctor of Medicine),
``D.O.'' (Doctor of Osteopathy), ``C.N.M.'' (certified nurse midwife), ``Other midwife,'' and ``Other''
attendants. In earlier certificates births attended by certified nurse midwives were grouped with those
attended by lay midwives. The new certificate also facilitates the identification of home births, births
in freestanding birthing centers, and births in clinics or physician offices. 
Data for the ``In hospital'' category for 1975-88 include all births in clinics or maternity
centers, regardless of the attendant. Data for 1975-77 published before 1980 included clinic and
center births in the category ``In hospital'' only when the attendant was a physician. Data shown for
1975-77 published after 1980 will, therefore, differ from data published before 1980. As a result of
this change, for 1975 an additional 12,352 births are now classified as occurring in hospitals, raising
the percent of births occurring in hospitals from 98.7 to 99.1. Similarly, for 1976 the number of
births occurring in hospitals increased by 14,133 and the percent in hospitals raised from 98.6 to
99.1; for 1977 the increase is 15,937 and the percent in hospitals raised from 98.5 to 99.0. For 1974
and earlier the ``In hospital'' category includes all births in hospitals or institutions and births in
clinics, centers, or maternity homes only when attended by physicians.
The ``Not in hospital'' category includes births for which no information is reported on place
of birth. Before 1975 births for which the stated place of birth was a ``doctor's office'' and delivery
was by a physician were included in the category ``In hospital.''  Beginning in 1975 these births were
tabulated as ``Not in hospital'' and included with births delivered by physicians in this category.
Although the actual number of such births is unknown, the effect of the change is minimal. In 1974,
0.3 percent of all births were delivered by physicians outside of hospitals; in 1975 this proportion
was 0.4 percent.
Babies born on the way to or on arrival at the hospital are classified as having been born in
the hospital. This may account for some of the hospital births not delivered by physicians or
midwives.  
Beginning in 1993, all in-hospital births occurring in Illinois where the attendant was
classified as  an "other" midwife were changed to certified nurse-midwife.  This was necessary
because almost all of these births were delivered by midwives certified by the American College of
Nurse Midwives but because Illinois does not certify midwives, many of these births were classified
as "other" midwives.
Birthweight 
Birthweight is reported in some areas in pounds and ounces rather than in grams. However,
the metric system has been used in tabulating and presenting the statistics to facilitate comparison
with data published by other groups. The categories for birthweight were changed in 1979 to be
consistent with the recommendations in the Ninth Revision of the International Classification of
Diseases (ICD-9).  The categories in gram intervals and their equivalents in pounds and ounces are
as follows:
 Less than 500 grams = 1 lb 1 oz or less
500-999 grams = 1 lb 2 oz-2 lb 3 oz
1,000-1,499 grams = 2 lb 4 oz-3 lb 4 oz
1,500-1,999 grams = 3 lb 5 oz-4 lb 6 oz
2,000-2,499 grams = 4 lb 7 oz-5 lb 8 oz
2,500-2,999 grams = 5 lb 9 oz-6 lb 9 oz
3,000-3,499 grams = 6 lb 10 oz-7 lb 11 oz
3,500-3,999 grams = 7 lb 12 oz-8 lb 13 oz
4,000-4,499 grams = 8 lb l4 oz-9 lb l4 oz
4,500-4,999 grams = 9 lb 15 oz-11 lb 0 oz
5,000 grams or more = 11 lb l oz or more
The ICD-9 defines low birthweight as less than 2,500 grams. This is a shift of 1 gram from
the previous criterion of 2,500 grams or less, which was recommended by the American Academy
of Pediatrics in 1935 and adopted in 1948 by the World Health Organization in the Sixth Revision
of the International Lists of Diseases and Causes of Death.
After data classified by pounds and ounces are converted to grams, median weights are
computed and rounded before publication. To establish the continuity of class intervals needed to
convert pounds and ounces to grams, the end points of these intervals are assumed to be half an
ounce less at the lower end and half an ounce more at the upper end. For example, 2 lb 4 oz-3 lb 4
oz is interpreted as 2 lb 3 1/2 oz-3 lb 4 1/2 oz.  Births for which birthweight is not reported are
excluded from the computation of percents and medians. 
Period of gestation 
The period of gestation is defined as beginning with the first day of the last normal menstrual
period (LMP) and ending with the day of the birth. The LMP is used as the initial date because it can
be more accurately determined than the date of conception, which usually occurs 2 weeks after the
LMP.
Births occurring before 37 completed weeks of gestation are considered to be ``preterm'' or
``premature'' for purposes of classification.  At 37-41 weeks gestation, births are considered to be
``term,'' and at 42 completed weeks and over, ``postterm.'' These distinctions are according to the
ICD-9 definitions.
The 1989 revision of the U.S. Standard Certificate of Live Birth included a new item,
``clinical estimate of gestation,'' that is being compared with length of gestation computed from the
LMP date when the latter appears to be inconsistent with birthweight. This is done for normal-weight
births of apparently short gestations and very low-birthweight births reported to be full term. The
clinical estimate also was used if the date of the LMP was not reported. The period of gestation for
4.1 percent of the births in 1994 was based on the clinical estimate of gestation. For 96 percent of
these records the clinical estimate was used because the LMP date was not reported. For the
remaining 4 percent the clinical estimate was used because it was compatible with the reported
birthweight, whereas the LMP-computed gestation was not. In cases where the reported birthweight
was inconsistent with both the LMP-computed gestation and the clinical estimate of gestation, the
LMP-computed gestation was used if it was within 5 weeks of the clinical  estimate and birthweight
was reclassified as ``not stated.''  If the reported birthweight was inconsistent with both the LMP-
computed gestation and the clinical estimate of gestation, gestation and birthweight were classified
as "not stated" if the LMP-computed gestation was not within 5 weeks of the clinical estimate. 
These changes result in only a very small discontinuity in the data. For further information on the
use of the clinical estimate of gestation see ``Computer Edits for Natality Data, Effective 1989,''
NCHS Instruction Manual , Part 12, pages 34-36.
Before 1981 the period of gestation was computed only when there was a valid month, day,
and year of LMP. However, length of gestation could not be determined from a substantial number
of live-birth certificates each year because the day of LMP was missing. Beginning in 1981 weeks
of gestation have been imputed for records with missing day of LMP when there is a valid month
and year. Each such record is assigned the gestational period in weeks of the preceding record that
has a complete LMP date with the same computed months of gestation and the same 500-gram
birthweight interval. The effect of the imputation procedure is to increase slightly the proportion of
preterm births and to lower the proportion of births at 39, 40, 41, and 42 weeks of gestation. A
more complete discussion of this procedure and its implications is presented in a previous report
(13). 
Because of postconception bleeding or menstrual irregularities, the presumed date of LMP
may be in error. In these instances the computed gestational period may be longer or shorter than the
true gestational period, but the extent of such errors is unknown. 
Month of pregnancy prenatal care began 
For those records in which the name of the month is entered for this item, instead of first,
second, third, and so forth, the month of pregnancy in which prenatal care began is determined from
the month named and the month last normal menses began. For these births, if the item ``Date last
normal menses began'' is not stated, the month of pregnancy in which prenatal care began is tabulated
as not stated.  
Number of prenatal visits 
Tabulations of the number of prenatal visits were presented for the first time in 1972.
Beginning in 1989 these data were collected from the birth certificates of all States. Percent
distributions and the median number of prenatal visits exclude births to mothers who had no prenatal
care.  
Apgar score 
One- and 5-minute Apgar scores were added to the U.S. Standard Certificate of Live Birth
in 1978 to evaluate the condition of the newborn infant at 1 and 5 minutes after birth. The Apgar
score is a useful measure of the need for resuscitation and a predictor of the infant's chances of
surviving the first year of life. It is a summary measure of the infant's condition based on heart rate,
respiratory effort, muscle tone, reflex irritability, and color. Each of these factors is given a score of
0, 1, or 2; the sum of these 5 values is the Apgar score, which ranges from 0 to 10. A score of 10 is
optimum, and a low score raises some doubts about the survival and subsequent health of the infant.
In 1994 the reporting area for the 1- and 5-minute Apgar scores was comprised of 48 States and the
District of Columbia, accounting for 78 percent of all births in the United States.  California and
Texas did not have information on Apgar scores on their birth certificate.     
Tobacco and alcohol use during pregnancy 
The checkbox format allows for classification of a mother as a smoker or drinker during
pregnancy and for reporting the average number of cigarettes smoked per day or drinks consumed
per week. When smoking and/or drinking status is not reported or is inconsistent with the quantity
of cigarettes or drinks reported, the status is changed to be consistent with the amount reported. For
example, if the drinking status is reported as ``no'' but one or more average drinks a week are
reported, the mother is classified as a drinker. If the number of cigarettes smoked per day is reported
as one or more, the mother is considered a smoker. When one (or a fraction of one) drink a week is
recorded, the mother is classified as a drinker. For records on which the number of drinks or number
of cigarettes is reported as a span, for example, 10-15, the lower number is used. The number of
drinkers and number of drinks reported on birth certificates are believed to underestimate actual
alcohol use. 
Data on tobacco use were collected by 46 States, the District of Columbia, and New York
City in 1994.  This reporting area accounted for 79 percent of all births in the U.S. in 1994. 
Information on alcohol use was included on the certificates of 48 States and the District of Columbia,
accounting for 85 percent of all U.S. births in 1994.  California and South Dakota did not include
items on alcohol use of their birth certificates.   
Weight gained during pregnancy 
Weight gain is reported in pounds. A loss of weight is reported as zero gain. Computations
of median weight gain were based on ungrouped data. This item was included on the certificates of
49 States and the District of Columbia; California did not report this information.  This reporting
area excluding California accounted for 86 percent of all births in the United States in 1994.   
Medical risk factors for this pregnancy 
In 1994 an item on medical risk factors was included on the birth certificates of all States and
the District of Columbia, but two States did not report all of the 16 risk factors.  Texas did not report
genital herpes or uterine bleeding while Kansas did not report Rh sensitization.  
The format allows for the designation of more than one risk factor and includes a choice of
``None.'' Accordingly, if the item is not completed, it is classified as ``Not stated.''
The following definitions are adapted and abbreviated from a set of definitions compiled by
a committee of Federal and State health statistics officials for the Association for Vital Records and
Health Statistics (14). 
Definitions of medical terms 
Anemia--Hemoglobin level of less than 10.0 g/dL during pregnancy or a hematocrit of less than 30
percent during pregnancy.

Cardiac disease--Disease of the heart.
Acute or chronic lung disease--Disease of the lungs during pregnancy.

Diabetes--Metabolic disorder characterized by excessive discharge of urine and persistent thirst;
includes juvenile onset, adult onset, and gestational diabetes during pregnancy.

Genital herpes--Infection of the skin of the genital area by herpes simplex virus.

Hydramnios/Oligohydramnios--Any noticeable excess (hydramnios) or lack (oligohydramnios) of
amniotic fluid. 

Hemoglobinopathy--A blood disorder caused by alteration in the genetically determined molecular
structure of hemoglobin (for example, sickle cell anemia).

Hypertension, chronic--Blood pressure persistently greater than 140/90, diagnosed prior to onset of
pregnancy or before the 20th week of gestation.

Hypertension, pregnancy-associated--An increase in blood pressure of at least 30 mm Hg systolic
or 15 mm Hg diastolic on two measurements taken 6 hours apart after the 20th week of gestation.

Eclampsia--The occurrence of convulsions and/or coma unrelated to other cerebral conditions in
women with signs and symptoms of pre-eclampsia.

Incompetent cervix--Characterized by painless dilation of the cervix in the second trimester or early
in the third trimester of pregnancy, with prolapse of membranes through the cervix and ballooning
of the membranes into the vagina, followed by rupture of membranes and subsequent expulsion of
the fetus.

Previous infant 4,000+ grams--The birthweight of a previous live-born child was over 4,000 grams
(8 lbs 13 oz).

Previous preterm or small-for-gestational-age infant--Previous birth of an infant prior to term (before
37 completed weeks of gestation) or of an infant weighing less than the 10th percentile for
gestational age using a standard weight-for-age chart.

Renal disease--Kidney disease.

Rh sensitization--The process or state of becoming sensitized to the Rh factor as when an
Rh-negative woman is pregnant with an Rh-positive fetus.

Uterine bleeding--Any clinically significant bleeding during the pregnancy, taking into consideration
the stage of pregnancy; any second or third trimester bleeding of the uterus prior to the onset of
labor. 
Obstetric procedures 
This item includes six specific obstetric procedures. Birth records with ``Obstetric
procedures'' left blank are considered ``not stated.''   Data on obstetric procedures were reported by
all States and the District of Columbia. 
The following definitions are adapted and abbreviated from a set of definitions compiled by
a committee of Federal and State health statistics officials for the National Association for Public
Health Statistics and Information Systems (NAPHSIS), formerly the Association for Vital Records
and Health Statistics (14). 
Definitions of medical terms 
Amniocentesis--Surgical transabdominal perforation of the uterus to obtain amniotic fluid to be used
in the detection of genetic disorders, fetal abnormalities, and fetal lung maturity.
Electronic fetal monitoring--Monitoring with external devices applied to the maternal abdomen or
with internal devices with an electrode attached to the fetal scalp and a catheter through the cervix
into the uterus, to detect and record fetal heart tones and uterine contractions.
Induction of labor--The initiation of uterine contractions before the spontaneous onset of labor by
medical and/or surgical means for the purpose of delivery.
Stimulation of labor--Augmentation of previously established labor by use of oxytocin.
Tocolysis--Use of medications to inhibit preterm uterine contractions to extend the length of
pregnancy and therefore avoid a preterm birth.
Ultrasound--Visualization of the fetus and placenta by means of sound waves. 
Complications of labor and/or delivery 
The checkbox format allows for the selection of 15 specific complications and for the designation
of more than 1 complication where appropriate. A choice of ``None'' is also included. Accordingly,
if the item is not completed, it is classified as ``not stated.''
All States and the District of Columbia included this item on their birth certificates. However,
not all of the complications were reported by all reporting States (see table A). 
The following definitions are adapted and abbreviated from a set of definitions compiled by
a committee of Federal and State health statistics officials. (14). 

Definitions of medical terms 
Febrile--A fever greater than 100 degrees F. or 38 C. occurring during labor and/or delivery.

Meconium, moderate/heavy--Meconium consists of undigested debris from swallowed amniotic
fluid, various products of secretion, excretion, and shedding by the gastrointestinal tract; moderate
to heavy amounts of meconium in the amniotic fluid noted during labor and/or delivery.
Premature rupture of membranes (more than 12 hours)--Rupture of the membranes at any time
during pregnancy and more than 12 hours before the onset of labor.

Abruptio placenta--Premature separation of a normally implanted placenta from the uterus.

Placenta previa--Implantation of the placenta over or near the internal opening of the cervix.

Other excessive bleeding--The loss of a significant amount of blood from conditions other than
abruptio placenta or placenta previa.

Seizures during labor--Maternal seizures occurring during labor from any cause.
Precipitous labor (less than 3 hours)--Extremely rapid labor and delivery lasting less than 3 hours.
Prolonged labor (more than 20 hours)--Abnormally slow progress of labor lasting more than 20
hours.

Dysfunctional labor--Failure to progress in a normal pattern of labor.

Breech/Malpresentation--At birth, the presentation of the fetal buttocks rather than the head, or other
malpresentation. 

Cephalopelvic disproportion--The relationship of the size, presentation, and position of the fetal head
to the maternal pelvis prevents dilation of the cervix and/or descent of the fetal head.
Cord prolapse--Premature expulsion of the umbilical cord in labor before the fetus is delivered.

Anesthetic complications--Any complication during labor and/or delivery brought on by an
anesthetic agent or agents.

Fetal distress--Signs indicating fetal hypoxia (deficiency in amount of oxygen reaching fetal tissues). 
Abnormal conditions of the newborn 
This item provides information on eight specific abnormal conditions. More than one
abnormal condition may be reported for a given birth or ``None'' may be selected. If the item is not
completed it is tabulated as ``not stated.'' This item was included on the birth certificates of all States
and the District of Columbia in 1994.  However, several States did not include all conditions (see
table A).
The following definitions are adapted and abbreviated from a set of definitions compiled by
a committee of Federal and State health statistics. (14). 
Definitions of medical terms 
Anemia--Hemoglobin level of less than 13.0 g/dL or a hematocrit of less than 39 percent.

Birth injury--Impairment of the infant's body function or structure due to adverse influences that
occurred at birth.

Fetal alcohol syndrome--A syndrome of altered prenatal growth and development occurring in
infants born of women who consumed excessive amounts of alcohol during pregnancy.

Hyaline membrane disease/RDS--A disorder primarily of prematurity, manifested clinically by
respiratory distress and pathologically by pulmonary hyaline membranes and incomplete expansion
of the lungs at birth.

Meconium aspiration syndrome--Aspiration of meconium by the fetus or newborn, affecting the
lower respiratory system.
Assisted ventilation (less than 30 minutes)--A mechanical method of assisting respiration for
newborns with respiratory failure. 
Assisted ventilation (30 minutes or more)--Newborn placed on assisted ventilation for 30 minutes
or longer.

Seizures--A seizure of any etiology. 
Congenital anomalies of child 
The data provided in this item relate to 21 specific anomalies or anomaly groups. It is well
documented that congenital anomalies, except for the most visible and most severe, are incompletely
reported on birth certificates. The completeness of reporting specific anomalies depends on how
easily they are recognized in the short time between birth and birth registration. Forty-nine States and
the District of Columbia included this item on their birth certificates (New Mexico and New York
City did not).  This reporting area included 96 percent of all births in the United States in 1994.  The
format allows for the identification of more than one anomaly including a choice of ``None'' should
no anomalies be evident. The category ``not stated'' includes birth records for which the item is not
completed. 
The following definitions are adapted and abbreviated from a set of definitions compiled by
a committee of Federal and State health statistics officials. (14). 
Definitions of medical terms 
Anencephalus--Absence of the cerebral hemispheres.

Spina bifida/meningocele--Developmental anomaly characterized by defective closure of the bony
encasement of the spinal cord, through which the cord and meninges may or may not protrude.

Hydrocephalus--Excessive accumulation of cerebrospinal fluid within the ventricles of the brain with
consequent enlargement of the cranium.

Microcephalus--A significantly small head.
Other central nervous system anomalies--Other specified anomalies of the brain, spinal cord, and
nervous system.

Heart malformations--Congenital anomalies of the heart.
Other circulatory/respiratory anomalies--Other specified anomalies of the circulatory and respiratory
systems.

Rectal atresia/stenosis--Congenital absence, closure, or narrowing of the rectum.

Tracheo-esophageal fistula/Esophageal atresia--An abnormal passage between the trachea and the
esophagus; esophageal atresia is the congenital absence or closure of the esophagus.

Omphalocele/gastroschisis--An omphalocele is a protrusion of variable amounts of abdominal
viscera from a midline defect at the base of the umbilicus. In gastroschisis, the abdominal viscera
protrude
through an abdominal wall defect, usually on the right side of the umbilical cord insertion.

Other gastrointestinal anomalies--Other specified congenital anomalies of the gastrointestinal
system.

Malformed genitalia--Congenital anomalies of the reproductive organs.

Renal agenesis--One or both kidneys are completely absent.

Other urogenital anomalies--Other specified congenital anomalies of the organs concerned in the
production and excretion of urine, together with organs of reproduction.

Cleft lip/palate--Cleft lip is a fissure of elongated opening of the lip; cleft palate is a fissure in the
roof of the mouth.  These are failures of embryonic development.

Polydactyly/syndactyly/adactyly--Polydactyly is the presence of more than five digits on either hands
and/or feet; syndactyly is having fused or webbed fingers and/or toes; adactyly is the absence of
fingers and/or toes.

Club foot--Deformities of the foot, which is twisted out of shape or position.

Diaphragmatic hernia-- Herniation of the abdominal contents through the diaphragm into the thoracic
cavity usually resulting in respiratory distress.

Other musculoskeletal/integumental anomalies--Other specified congenital anomalies of the muscles,
skeleton, or skin.

Down's syndrome--The most common chromosomal defect with most cases resulting from an extra
chromosome (trisomy 21).

Other chromosomal anomalies--All other chromosomal aberrations. 
Method of delivery 
The birth certificate contains a checkbox item on method of delivery. The choices include
vaginal delivery, with the additional options of forceps, vacuum, and vaginal birth after previous
cesarean section (VBAC), as well as a choice of primary or repeat cesarean. When only forceps,
vacuum, or VBAC is checked, a vaginal birth is assumed. In 1994 this information was collected
from the birth certificates of all States and the District of Columbia. 
Several rates are computed for method of delivery. The overall cesarean section rate or total
cesarean rate is computed as the proportion of all births that were delivered by cesarean section. The
primary cesarean rate is a measure that relates the number of women having a primary cesarean
delivery to all women giving birth who have never had a cesarean delivery. The denominator for this
rate includes all births, less those with method of delivery classified as repeat cesareans and vaginal
birth after previous cesarean. The rate for vaginal birth after previous cesarean (VBAC) delivery is
computed by relating all VBAC deliveries to the sum of VBAC and repeat cesarean deliveries, that
is, to women with a previous cesarean section.  VBAC rates for first births exist because the rates
are computed on the basis of previous pregnancies, not just live births. 
Hispanic parentage 
The 1989 revision of the U.S. Standard Certificate of Live Births includes items to identify
the Hispanic origin of the parents.  Concurrent with the 1978 revision of the U.S. Certificate of Live
Birth, NCHS recommended that items to identify the Hispanic or ethnic origin of the newborn's
parents be included on birth certificates and has tabulated and evaluated these data from the reporting
States.  All 50 States and the District of Columbia reported Hispanic origin of the parents for 1994. 

In computing birth and fertility rates for the Hispanic population, births with origin of mother
not stated are included with non-Hispanic births rather than being distributed. Thus, rates for the
Hispanic population are underestimates of the true rates to the extent that the births with origin of
mother not stated (1.1 percent in 1994) were actually to Hispanic mothers.  The population with
origin not stated was imputed. The effect on the rates is believed to be small. 
Quality of data 
Although vital statistics data are useful for a variety of administrative and scientific purposes,
they cannot be correctly interpreted unless various qualifying factors and methods of classification
are taken into account. The factors to be considered depend on the specific purposes for which the
data are to be used. It is not feasible to discuss all the pertinent factors in the use of vital statistics
tabulations, but some of the more important ones should be mentioned.
Most of the factors limiting the use of data arise from imperfections in the original records
or from the impracticability of tabulating these data in very detailed categories. These limitations
should not be ignored, but their existence does not lessen the value of the data for most general
purposes.  
Completeness of registration 
An estimated 99 percent of all births occurring in the United States in 1994 were registered;
for white births registration was 99.4 percent complete and for all other births, 98.6 percent
complete. These estimates are based on the results of the 1964-68 test of birth-registration
completeness according to place of delivery (in or out of hospital) and race and on the 1989
proportions of births in these categories. The primary purpose of the test was to obtain current
measures of registration completeness for births in and out of hospital by race on a national basis.
Data for States were not available as they had been from the previous birth-registration tests in 1940
and 1950. A detailed discussion of the method and results of the 1964-68 birth-registration test is
available (15).
The 1964-68 test has provided an opportunity to revise the estimates of birth-registration
completeness for the years since the previous test in 1950 to reflect the improvement in registration.
This has been done using registration completeness figures from the two tests by place of delivery
and race. Estimates of registration completeness for four groups (based on place of delivery and race)
for 1951-65 were computed by interpolation between the test results. (It was assumed that the data
from the more recent test are for 1966, the midpoint of the test period.) The results of the 1964-68
test are assumed to prevail for 1966 and later years. These estimates were used with the proportions
of births registered in these categories to obtain revised numbers of births adjusted for
underregistration for each year. The overall percent of birth-registration completeness by race was
then computed.      Data adjusted for underregistration for 1951-59 have been revised to be
consistent with the 1964-68 test results and differ slightly from data shown in annual reports for
years before 1969. For these years the published number of births and birth rates for both racial
groups have been revised slightly downward because the 1964-68 test indicated that previous
adjustments to registered births were slightly inflated. Because registration completeness figures by
age of mother and by live-birth order are not available from the 1964-68 test, it must be assumed that
the relationships among these variables have not changed since 1950.
Discontinuation of adjustment for underregistration, 1960--
Adjustment for underregistration of births was discontinued in 1960 when birth registration
for the United States was estimated to be 99.1 percent complete. This removed a bias introduced into
age-specific rates when adjusted births classified by age were used.  Age-specific rates are calculated
by dividing the number of births to an age group of mothers by the population of women in that age
group.  Tests have shown that population figures are likely to be understated through census
undercounts; these errors compensate for underregistration of births. Adjustment for
underregistration of births, therefore, removes the compensating effect of underenumeration, biasing
the age-specific rates more than when uncorrected birth and population data are used. (For further
details see page 4-11 in the Technical Appendix of volume I, Vital Statistics of the United States,
1963.) 
The age-specific rates used in the cohort fertility tables are an exception to the above
statement. These rates are computed from births corrected for underregistration and population
estimates adjusted for underenumeration and misstatement of age.
Adjusted birth and population estimates are used for the cohort rates because they are an integral part
of a series of rates, estimated with a consistent methodology. It was considered desirable to maintain
consistency with respect to the cohort rates, even though it means that they will not be precisely
comparable with other rates shown for 5-year age groups. 
Completeness of reporting 
Interpretation of these data must include evaluation of item completeness. The percent ``not
stated'' is one measure of the quality of the data. Completeness of reporting varies among items and
States. See table A for the percent of birth records on which specified items were not stated. 
Quality control procedures 
States in the Vital Statistics Cooperative Program are required to have an error rate of less
than 2.0 percent for each item for 3 consecutive data months during the initial qualifying period.
Once a State is qualified, NCHS monitors the quality of data received.  This was achieved through
independent verification of a sample of records for some States as well as comparing the State data
with data from previous years.  In addition, there is verification at the State level before NCHS is
sent the data.

After the coding is completed, counts of the taped records are balanced against control totals
for each shipment of records from a registration area. Impossible codes are eliminated during the
editing processes on the computer and corrected on the basis of reference to the source record or
adjusted by arbitrary code assignment. All subsequent operations involved in tabulation and table
preparation are verified during computer processing or by statistical clerks. 
Small frequencies 
The numbers of births reported for an area represent complete counts. As such, they are not
subject to sampling error, although they are subject to errors in the registration process. However,
when the figures are used for analytical purposes, such as the comparison of rates over a period of
time or for different areas, the number of events that actually occurred may be considered as one of
a large series of possible results that could have arisen under the same circumstances. The probable
range of values may be estimated from the actual figures according to certain statistical assumptions.
In general, distributions of vital events may be assumed to follow the binomial distribution.
Estimates of standard errors and tests of significance under this assumption are described in most
standard statistics texts. When the number of events is large, the relative standard error, expressed
as a percent of the number or rate, is usually small.
When the number of events is small (fewer than 100) and the probability of such an event
is small, considerable caution must be observed in interpreting the conditions described by the
figures.  Events of rare nature may be assumed to follow a Poisson probability distribution. For this
distribution, a simple approximation may be used to estimate the error as follows: 
If N is the number of births and R is the corresponding rate, the chances are 19 in 20 that 
1. The ``true'' number of events lies between SQRT 
   N~-~2SQRT{N}~\and~N~+~2SQRT{N}
2. The ``true'' rate lies between 
   R~-~2{R over SQRT{N}}~\and~R~+~2{R over SQRT{N}}

If the rate R1 corresponding to N1 events is compared with the rate R2 corresponding to 
N2 events, the difference between the two rates may be regarded as statistically significant 
if it exceeds 
 
   2~sqrt{{R_1^2 over N_1}~+~{R_2^2 over N_2}}


For example, suppose that the observed birth rate for area A was 15.0 per 1,000 population and that
this rate was based on 50 recorded births. Given prevailing conditions, the chances are 19 in 20 that
the ``true'' or underlying birth rate for that area lies between 10.8 and 19.2 per 1,000 population. Let
it be further supposed that the birth rate for area A of 15.0 per 1,000 population is being compared
with a rate of 20.0 per 1,000 population for area B, which is based on 40 recorded births. Although
the difference between the rates for the two areas is 5.0, this difference is less than twice the standard
error of the difference
  2~sqrt{{{(15.0)^2} over 50}~+~{{(20.0)^2} over 40}}


of the two rates that is computed to be 7.6. From this, it is concluded that the difference between the
rates for the two areas is not statistically significant. 
Computation of rates and other measures 
Population bases 
The rates shown in this report were computed on the basis of population statistics prepared
by the U.S. Bureau of the Census. Rates for 1940, 1950, 1960, 1970, 1980, and 1990 are based on
the population enumerated as of April 1 in the censuses of those years. Rates for all other years are
based on the estimated midyear (July 1) population for the respective years. Birth rates for the United
States, individual States, and metropolitan areas are based on the total resident populations of the
respective areas. Except as noted these populations exclude the Armed Forces abroad but include
the Armed Forces stationed in each area.
The resident population of the birth- and death-registration States for 1900-32 and for the
United States for 1900-94 is shown in table 4-1.  In addition, the population including Armed Forces
abroad is shown for the United States. Table B shows the sources for these populations.
In both the 1980 and 1990 censuses, a substantial number of persons did not specify a racial
group that could be classified as any of the White, Black, American Indian, Eskimo, Aleut, Asian,
or Pacific Islander categories on the census form (16). In 1980 the number of persons of ``other'' race
was 6,758,319; in 1990 it was 9,804,847. In both censuses, the large majority of these persons were
of Hispanic origin (based on response to a separate question on the form), and many wrote in their
Hispanic origin, or Hispanic origin type (for example, Mexican, Puerto Rican) as their race. In both
1980 and 1990, persons of unspecified race were allocated to one of the four tabulated racial groups
(white, black, American Indian, Asian or Pacific Islander), based on their response to the Hispanic
origin question. These four race categories conform with the 1979 edition of OMB Directive 15
which mandates that race data must contain at least these 4 categories.  These categories are also
more consistent with the race categories in vital statistics.
In the allocation of unspecified race was carried out using cross-tabulations of age, sex, race,
type of Hispanic origin, and county of residence. Persons of Hispanic origin and unspecified race
were allocated to either white or black, based on their Hispanic origin type. Persons of ``other'' race
and Mexican origin were categorically assumed to be white, while persons in other Hispanic
categories were distributed to white and black pro rata within the county-age-sex group. For
``other-not-specified'' persons who were not Hispanic, race was allocated to white, black, or Asian
and Pacific Islander, based on proportions gleaned from sample data. The 20-percent sample
(respondents who were enumerated on the longer census form) provided a highly detailed coding of
race, which allowed identification of otherwise unidentifiable responses with a specified race
category.  Allocation proportions were thus established at the State level, which were used to
distribute the non-Hispanic persons of ``other'' race in the 100-percent tabulations.
In 1990 the race modification procedure was carried out using individual census records.
Persons whose race could not be specified were assigned to a racial category using a pool of ``race
donors,'' which was derived from persons of specified race and the identical response to the Hispanic
origin question within the auspices of the same Census District Office. As in 1980, the underlying
assumption was that the Hispanic origin response was the major criterion for allocating race. Unlike
1980, persons of Hispanic origin, including Mexican, could be assigned to any racial group, rather
than white or black only, and the non-Hispanic component of ``other'' race was allocated primarily
on the basis of geography (District Office), rather than detailed characteristic.
The means by which respondent's age was determined were fundamentally different in the
two censuses; therefore, the problems that necessitated the modification were different. In 1980
respondents reported year of birth and quarter of birth (within year) on the census form. When census
results were tabulated, persons born in the first quarter of the year (before April 1) had age equal to
1980 minus year of birth, while persons born in the last three quarters had age equal to 1979 minus
year of birth.
In 1990 the quarter year of birth was not reported on the census form, so that direct
determination of age from year of birth was impossible.  In 1990 census publications age is based
on respondents' direct reports of age at last birthday. This definition proved inadequate for postcensal
estimates, because it was apparent that many respondents had reported their age at time of either
completion of the census form or interview by an enumerator, which could occur several months
after the April 1 reference data. As a result, age was biased upward.  Modification was based on a
respecification of age, for most individual respondents, by year of birth, with allocation to first
quarter(persons aged 1990 minus year of birth) and last three quarters (aged 1989 minus year of birth) based
on a historical series of registered births by month. This process partially restored the 1980 logic for
assignment of age. It was not considered necessary to correct for age overstatement and heaping in
1990, because the availability of age and year of birth on the census form provided elimination of
spurious year-of-birth reports in the census data before modification occurred. 
Populations for 1994--The population of the United States by age, sex, race, and Hispanic origin are
shown in the Census Bureau report, United States population estimates by age, sex, race and
Hispanic origin: 1990 to 1994. U.S. Bureau of the Census. PPL-21. Washington: U.S. Department
of Commerce. 1995.
Populations for 1993--The population of the United States by age, sex, race and Hispanic origin are
tabulated from Census file RESO793.  Washington: U.S. Department of Commerce. 1995.
Populations for 1992--The population of the United States by age, sex, race and Hispanic origin are
tabulated from census file RESPO792.  Washington: U.S. Department of Commerce. 1994. 
Populations for 1991--The population of the United States by age, race, and sex are shown in Current
Population Reports, Series P-25, Number 1095. Monthly population figures were published in
Current Population Reports, Series P-25, Number 1097.
Populations for 1990--The population of the United States by age, race, and sex, and the population
for each State are shown in Current Population Reports, Series P-25, Number 1095. The figures have
been modified as described above. Monthly population figures were published in Current Population
Reports, Series P-25, Number 1094.
Population estimates for 1981-89--Birth rates for 1981-89 (except those for cohorts of women) have
been revised, based on revised population estimates that are consistent with the 1990 census levels,
and thus may differ from rates published in volumes of Vital Statistics of the United States for these
years. The 1990 census counted approximately 1.5 million fewer persons than had earlier been
estimated for April 1, 1990. The revised estimates for the United States by age, race, and sex were
published by the U.S. Bureau of the Census in Current Population Reports, Series P-25, Number
1095. Population estimates by month are based on data published in Current Population Reports,
Series P-25, Number 1094 and unpublished data. Unpublished revised estimates for States were
obtained from the U.S. Bureau of the Census.
Populations for 1980--The population of the United States by age, race, and sex, and the population
for each State are shown in tables 4-2 and 4-3 of volume I, Vital Statistics of the United States, 1980.
The figures by race have been modified as described above. Monthly population figures were
published in Current Population Reports, Series P-25, Number 899.
Population estimates for 1971-79--Birth rates for 1971-79 (except those for cohorts of women) have
been revised, based on revised population estimates that are consistent with the 1980 census levels,
and thus may differ from rates published in volumes of Vital Statistics of the United States for these
years. The 1980 census counted approximately 5.5 million more persons than had earlier been
estimated for April 1, 1980 (17). The revised estimates for the United States by age, race, and sex
were published by the U.S. Bureau of the Census in Current Population Reports, Series P-25,
Number 917. Population estimates by month are based on data published in Current Population
Reports, Series P-25, Number 899. Unpublished revised estimates for States were obtained from the
U.S. Bureau of the Census.
Population estimates for 1961-69--Birth rates for 1961-69 are based on revised estimates of the
population and thus may differ slightly from rates published before 1976. The revised estimates used
in computing these rates were published in Current Population Reports, Series P-25, Number 519.
The rates for 1961-64 are based on revised estimates of the population published in Current
Population Reports, Series P-25, Numbers 321 and 324 and may differ slightly from rates published
in those years.
Population estimates for 1951-59--Final intercensal estimates of the population by age, race, and sex
and total population by State for 1951-59 are shown in tables 4-4 and 4-5 of volume I, Vital Statistics
of the United States, 1966. Beginning with 1963 these final estimates have been used to compute
birth rates for 1951-59 in all issues of Vital Statistics of the United States. 
Net census undercounts and overcounts 
The U.S. Bureau of the Census has conducted extensive research to evaluate the coverage
of the U.S. population (including undercount, overcount, and misstatement of age, race, and sex) in
the last five decennial censuses 1950, 1960, 1970, 1980, and 1990. These studies provide estimates
of the national population, that were not enumerated or overenumerated in the respective censuses,
by age, race, and sex (17-19). The report for 1990 (20) includes estimates of net underenumeration
and overenumeration for age, sex, and racial subgroups of the national population, modified for race
consistency with previous population counts as described in the section ``Population bases.''
These studies indicate that there are differential coverages in the censuses among the
population subgroups; that is, some age, race, and sex groups are more completely enumerated than
others. To the extent that these estimates of overcounts or undercounts are valid, that they are
substantial, and that they vary among subgroups and geographic areas, census miscounts can have
consequences for vital statistics measures (18). However, the effects of undercounts in the census
are reduced to the extent that there is underregistration of births. If these two factors are of equal
magnitude, rates based on unadjusted populations are more accurate than those based on adjusted
populations because the births have not been adjusted for underregistration. 
The impact of net census miscounts on vital statistics measures includes the effects on levels
of the rates and effects on differentials among groups.
If adjustments were made for persons who were not counted in the census of population, the
size of the denominators would generally increase and the rates would be smaller than without an
adjustment. Adjusted rates for 1990 can be computed by multiplying the reported rates by ratios of
the 1990 census-level population adjusted for the estimated net census miscounts, which are shown
in table C. A ratio of less than 1.0 indicates a net census undercount and would result in a
corresponding decrease in the rate. A ratio in excess of 1.0 indicates a net census overcount and
would result in a corresponding increase in the rate.
Enumeration of white females in the childbearing ages was at least 97 percent complete for
all ages. Among black women, the undercount ranged up to 5 percent. Generally, females in the
childbearing ages were more completely enumerated than males for similar race-age groups.
If vital statistics measures were calculated with adjustments for net census miscounts for each
of these subgroups, the resulting rates would have been differentially changed from their original
levels; that is, rates for those groups with the greatest estimated overcounts or undercounts would
show the greatest relative changes due to these adjustments. Thus the racial differential in fertility
between the white and the ``All other'' population can be affected by such adjustments. 
Cohort fertility tables 
The various fertility measures shown for cohorts of women are computed from births
adjusted for underregistration and population estimates corrected for underenumeration and
misstatement of age. Data published after 1974 use revised population estimates prepared by the U.S.
Bureau of the Census and have been expanded to include data for the two major racial groups.
Heuser has prepared a detailed description of the methods used in deriving these measures as well
as more detailed data for earlier years (21). 
Parity distribution--The percent distribution of women by parity (number of children ever born alive
to mother) is derived from cumulative birth rates by order of birth.  The percent of  zero-parity
women is found by subtracting the cumulative first birth rate from 1,000 and dividing by 10. The
proportions of women at parities one through six are found from the following formula: 
Percent at N parity = (cum. rate, order N) - (cum. rate, order N + 1)10
The percent of women at seventh higher parities is found by dividing the cumulative rate for
seventh-order births by 10. 
Birth probabilities--birth probabilities indicate the likelihood that a woman of a certain parity and
age at the beginning of the year will have a child during the year.  Birth probabilities differ from
central birth rates in that the denominator for birth probabilities is specific for parity as well as for
age. 
Age-sex-adjusted birth rates 
The age-sex-adjusted birth rates are computed by the direct method. The age distribution of
women aged 10-49 years as enumerated in 1940 and the total population of the United States for that
year are used as the standard populations. The age-sex-adjusted birth rates show differences in the
level of fertility independent of differences in the age and sex composition of the population. It is
important not to confuse these adjusted rates with the crude rates shown in other tables. 
Total fertility rate 
The total fertility rate is the sum of the birth rates by age of mother (in 5-year age groups)
multiplied by 5. It is an age-adjusted rate because it is based on the assumption that there are the
same number of women in each age group. The rate of 2,036 in 1994, for example, means that if a
hypothetical group of 1,000 women were to have the same birth rates in each age group that were
observed in the actual childbearing population in 1994, they would have a total of 2,036 children by
the time they reached the end of the reproductive period (taken here to be age 50 years), assuming
that all of the women survived to that age. 
Intrinsic vital rates 
The intrinsic vital rates are calculated from a stable population. A stable population is that
hypothetical population, closed to external migration, that would become fixed in age-sex structure
after repeated applications of a constant set of age-sex specific birth and death rates. For the
mathematical derivation of intrinsic vital rates, see pages 4-13 and 4-14 in the Technical Appendix
of volume I, Vital Statistics of the United States, 1962. The technique of calculating intrinsic vital
rates is described by Barclay (22). 
Seasonal adjustment of rates 
The seasonally adjusted birth and fertility rates are computed from the X-11 variant of
Census Method II (23).  This method of seasonal adjustment used since 1964 differs slightly from
the U.S. Bureau of Labor Statistics (BLS) Seasonal Factor Method, which was used for Vital
Statistics of the United States, 1964. The fundamental technique is the same in that it is an adaptation
of the ratio-to-moving-average method. Before 1964 the method of seasonal adjustment was based
on the X-9 variant and other variants of Census Method II. A comparison of the Census Method II
with the BLS Seasonal Factor Method shows the differences in the seasonal patterns of births to be
negligible. 
Computation of percents, medians, and means 
Percent distributions, medians, and means are computed using only events for which the
characteristic is reported. The ``Not stated'' category is subtracted from the total before computation
of these measures.  The asterisk (*) indicates that the numerator and/or denominator number
is less than 20. 
References 
1.  World Health Organization. Official records; no 28 (Third World Health Assembly 3.6).
    Geneva: World Health Organization, 16-17. 1950.  
2.   National Office of Vital Statistics. International recommendations on definitions of live birth
     and fetal deaths. Washington: Public Health Service. 1950. 
3.   Statistical Office of the United Nations. Principles for vital statistics system:
     Recommendations for the improvement and standardization of vital statistics. Doc.
     ST/STAT/SER.M/19. New York:  United Nations. 1953. 
4.   National Office of Vital Statistics. Births and birth rates in the entire United States, 1909 to
     1948. Vital Statistics--Special reports; vol 33 no 8. Washington: Public Health Service. 1950. 
5.   U.S. Bureau of the Census. Population of metropolitan areas and component geography:
     1990 and 1980 (6-30-90 definitions). 1990 CPH-L-10. Washington: U.S. Department of
     Commerce. 1991.
6.   U.S. Department of Commerce. Metropolitan statistical area classification. Federal Register;
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7.   U.S. Office of Management and Budget. Standard metropolitan statistical areas. Rev. ed.
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8.   U.S. Bureau of the Census.  1990 Census of Population. General population characteristics;
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9.   Martin JA. Birth characteristics for Asian or Pacific Islander subgroups, 1992. Monthly vital
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     Statistics. 1995.   
10.  Schachter J. Matched record comparison of birth certificate and census information in the
     United States, 1950. Vital statistics--Special Reports; vol 47 no12. Washington: Public
     Health Service. 1962. 
11.  Office of the State Registrar.  Michigan Department of Public Health.  Unpublished
     tabulation. 1995.   
12.  Ventura SJ. Births to unmarried mothers, United States, 1980-92. National Center for Health
     Statistics. Vital Health Stat 21(53). 1995. 
13.  Taffel S, Johnson D, Heuser R. A method for imputing length of gestation on birth
     certificates. National Center for Health Statistics.  Vital Health Stat 2(93). 1982. 
14.  Brockert JE, Stockbauer JW, Senner JW, et al. Recommended standard medical definitions
     for the U.S. Standard Certificate of Live Birth, 1989 revision. Paper presented at annual
     meeting of the Association for the Vital Record and Health Statistics. June 1990. 
15.  U.S. Bureau of the Census. Test of birth-registration completeness, 1964 to 1968. 1970
     census of population and housing; PHC (E)-2.  Evaluation and Research Program.
     Washington: U.S. Department of Commerce. 1973. 
16.  U.S. Bureau of the Census. U.S. population estimates, by age, sex, race, and Hispanic origin,
     1980-91. Current population reports; series P-25, no 1095. Washington: U.S. Department of
     Commerce. 1993. 
17.  U.S. Bureau of the Census. Coverage of the national population in the 1980 census by age,
     sex, and race. Preliminary estimates by demographic analysis. Current population reports;
     series P-23, no 115. Washington: U.S. Department of Commerce. 1982. 
18.  U.S. Bureau of the Census. Estimates of coverage of the population by sex, race, and
     age--Demographic analysis. 1970 census of population and housing; PHC (E)-4. Evaluation
     and Research Program. Washington: U.S. Department of Commerce. 1974.
19.  U.S. Bureau of the Census. Developmental estimates of the coverage of the population of
     States in the 1970 census-demographic analysis. Current population reports; series P-23, no
     65. Washington: U.S. Department of Commerce. 1977.
20.  Robinson JG, Ahmed B, Das Gupta P, et al. Estimation of population coverage in the 1990
     United States census based on demographic analysis. JASA 88(423):1061-71. 1993. 
21.  Heuser R. Fertility tables for birth cohorts by color: United States, 1917-73. Washington:
     National Center for Health Statistics. 1976. 
22.  Barclay GW. Techniques of population analysis. New York: John Wiley & Sons, Inc.,
     216-22. 1958. 
23.  U.S. Bureau of the Census. The X-11 variant of the Census Method II Seasonal Adjustment
     Program. Technical paper; no 15, 1967 rev. Washington: U.S. Department of Commerce.
     1967.



1995 Addendum to "Technical Appendix" of Vital Statistics of the United States, 1994" - 
Volume I, Natality
Apgar Score
In 1995, NCHS collected only the 5-minute Apgar score.  
Education of Father
In 1995, NCHS did not collect information on education of the father.
Birth Interval
In 1995, NCHS did not collect information on the date of last live birth.  Therefore, there is no
information on birth interval for 1995.  
Marital Status
In 1995, California and Nevada implemented procedures to help identify the mother's marital status
more accurately.  In California, procedures that were previously used to help identify the marital
status of Asian mothers was extended to Hispanic mothers also.  These procedures compare the
parents' surnanes when they are hyphenated if the parents were born in countries where naming
practices can identify the parents' marital status.  For Hispanic mothers, if the child is given a double
surname of the mother's and father's surnames (either entire surnames or portions of the parents'
hyphenated surnames), regardless of the sequence, and the mother is of Hispanic origin, the mother's
marital status is coded "Married".  In Nevada, marital status information is collected through the
electronic birth process even though there is not a direct question on marital status on the printed
birth certificate.  See the Technical Notes of the Report of Final Natality Statistics, 1995 for more
information on special procedures used by States to collect marital status information.
Percent Completeness
See table A for the percent completeness of all items collected from the birth certificate by NCHS
for each reporting area.
    

Linked Birth/Infant Death Data Set - 1995 Period Data
List of Data Elements and Locations
                       Denominator         Numerator   File       Unlinked
Data Items               File              Birth       Death       File
1.   General                  
  a. Year of birth            7-10           7-10      --        --
  b. Year of death            --             --        524-527   524-527
  c.  Resident status         11             11        505       505
  d.  Record weight           --             --        223-230   --
  e.  Flag for records included 
      in both numerator and 
      denominator             210            --        --        -- 
2.   Occurrence          
 a.   FIPS state              14-15               14-15          508-509   508-509
 b.   FIPS county             16-18               16-18          510-512   510-512
3.   Residence      
 a.   FIPS state              19-20               19-20          513-514   513-514
 b.   FIPS county             21-23               21-23          515-517   515-517
 c.   FIPS place              24-28               24-28          518-522   518-522
 d.   NCHS expanded state     12-13               12-13          506-507   506-507 
4.    Infant
      a.   Age                --                  --             211-214   211-214+
 b.   Race                    --                  --             --        35-38*
 c.   Sex                     78-79               78-79          --        78-79*
 d.   Gestation               70-77               70-77          --        --
 e.   Birthweight             80-87               80-87          --        --
 f.    Plurality              88-89               88-89          --        --
 g.   Apgar score             90-91               90-91          --        --
 h.   Day of week of birth/death  209             209            532       532     
 i.    Month of birth/death       205-206         205-206        528-529   528-529
5.    Mother
 a.   Age                     29-32               29-32          --        --
 b.   Race                    35-38               35-38          --        --
 c.   Education               39-41               39-41          --        --
 d.   Marital status          42-43               42-43          --        --
 e.   Place of birth          44-46               44-46          --        --
 f.    Hispanic origin        33-34               33-34          --        --
     
6.    Father
 a.   Age                     60-62               60-62          --        --
 b.   Race                    65-66               65-66          --        --
 c.   Hispanic origin         63-64               63-64          --        --
                                
                                
                              
Linked Birth/Infant Death Data Set - 1995 Period Data
List of Data Elements and Locations
                                Denominator        Numerator       File      Unlinked    
                                File               Birth           Death     File
Data Items                                                        
7.   Pregnancy items
  a.   Interval since last live 
       birth                       57-59          57-59          --          --
  b.   Month prenatal care began   51-53          51-53          --          --
  c.   Number of prenatal visits   54-55          54-55          --          --
  d.   Adequacy of care recode     56             56             --          --
  e.   Total birth order           47-48          47-48          --          --
  f.    Live birth order           49-50          49-50          --          --
          
8.     Medical and Health Data
  a.   Method of delivery          92-99          92-99          --          --
     
  b.   Medical risk factors        100-117        100-117        --          --
  c.   Other risk factors          
        Tobacco                    118-121        118-121        --          --
         Alcohol                   122-125        122-125        --          --
         Weight gain during 
         pregnancy                 126-128        126-128        --          --
  d.   Obstetric procedures        129-136        129-136        --          --
  e.   Complications of labor and/or
        delivery                   137-153        137-153        --          --
  f.    Abnormal conditions of the      
        newborn                    154-163        154-163        --          --
  g.   Congenital anomalies        164-186        164-186        --          --
  h.   Underlying cause of death   --             --             216-219     216-219
  i.    61 Infant cause recode     --             --             220-222     220-222
  j.    Multiple conditions        --             --             261-504     261-504   
9.     Other items       
  a.    Place of delivery          67             67             --          --
  b.    Attendant at birth         68             68             --          --
  c.    Hospital and patient status--             --             523         523
      
  e.    Place of accident          --             --             215         215
  f.     Residence reporting flags 187-203        187-203        --          --
+ For the unlinked file, date of birth as reported on the death certificate is used to generate   
  age at death.  See section on Changes Beginning with 1995 Data for explanation.  
* For the unlinked file, these items are from the death certificate.  See section on Changes       
  Beginning with 1995 Data for explanation.     




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